aylor looked bored. Lee Whitbread stared blankly at her, his hand halfway to the cigarette packet in front of him. Di Earnshaw was the only one who appeared interested in making a contribution. "I've heard it said that the incidence of arson is an index of the economic prosperity of a country. The more arson there is, the worse the economy is doing. Well, there's plenty unemployed round here," she said with the air of someone who expects to be ignored.

"And that's something we should bear in mind," Carol said, nodding with approval. "Now, this is what I want. A careful trawl through the over nights for CID and uniform for the last six months to see what we come up with. I want the victims re-interviewed to check if there are any obvious common factors, like the same insurance company. Sort it out among yourselves. I'll be having a chat with the fire chief before the four of us reconvene in ... shall we say three days? Fine. Any questions?"

"I could do the fire chief, ma'am," Di Earnshaw said eagerly. "I've had dealings with him before."

"Thanks for the offer, Di, but the sooner I make his acquaintance, the happier I'll feel."

Di Earnshaw's lips seemed to shrink inwards in disapproval, but she merely nodded.

"You want us to drop our other cases?" Tommy asked.

Carol's smile was sharp as an ice pick. She'd never had a soft spot for chancers. "Oh, please, Sergeant," she sighed. "I know what your case-load is. Like I said at the start of this conversation, it's Bradfield I came from. Seaford might not be the big city, but that's no reason for us to operate at village bobby pace."

She stood up, taking in the shock in their faces. "I didn't come here to fall out with people. But I will if I have to. If you think I'm a hard bastard to work for, watch me. However hard you work, you'll see me matching it. I'd like us to be a team. But we have to play my rules."

Then she was gone. Tommy Taylor scratched his jaw. "That's us told, then. Still think she's shag gable Lee?"

Di Earnshaw's thin mouth pursed. "Not unless you like singing falsetto."

"I don't think you'd feel a lot like singing," Lee said. "Anybody want that last Kitkat?"

Shaz rubbed her eyes and turned away from the computer screen. She'd come in early so she could squeeze in a quick revision of the previous day's software familiarization. Finding Tony at work on one of the other terminals had been a bonus. He'd looked astonished to see her walk through the door just after seven. "I thought I was the only workaholic insomniac around here," he'd greeted her.

"I'm crap on computers," she'd said gruffly, trying to cover her satisfaction at having him to herself. "I've always needed to work twice as hard to keep up."

Tony's eyebrows had jumped. Cops didn't generally admit weaknesses to an outsider. Either Shaz Bowman was even more unusual than he'd initially appreciated or else he was finally losing his alien status. "I thought everybody under thirty was a wizard on these," he said mildly.

"Sorry to disappoint you. I was behind the door when the anoraks were being handed out," Shaz replied. She settled in front of her screen and pushed up the sleeves of her cotton sweater. "First remember your password," she muttered, wondering what he thought of her.

Two forces seethed under Shaz Bowman's calm surface, taking it in turns to drive her. On the one hand, fear of failure gnawed at her, undermining everything she was and all she achieved. When she looked in the mirror, she never saw her good points, only the thinness of her lips and the lack of definition in her nose. When she reviewed her accomplishments, she saw only the places where she had fallen short, the heights she had failed to scale. The countervailing force was her ambition. Somehow, ever since she'd first begun to formulate the ambitions that drove her, those goals had restored her damaged self-confidence and shored up her vulnerabilities before they could cripple her. When her ambition threatened to tip her over into arrogance, somehow the fear would kick in at the crucial point, keeping her human.

The setting up of the task force had coincided so perfectly with the direction of her dreams, she couldn't help but feel the hand of fate in it. That didn't mean that she could let up, however. Shaz's long-term career plan meant she had to shine brighter than anyone else in this task force. One of her tactics for achieving that was to pick Tony Hill's brains like a master locksmith, extracting every scrap of knowledge she could scavenge there while simultaneously worming her way inside his de fences so that when she needed his help, he'd be willing to provide it. As part of her approach, and because she was terrified that otherwise she'd fall behind and make a fool of herself in a group that she was convinced were all better than her, she was covertly taping all the group sessions, listening to them over and over again whenever she could. And now, luck had dropped a bonus opportunity into her lap.

So Shaz frowned and stared at the screen, working her way through the lengthy process of filling out an offence report then setting in motion its comparison against the details of all the previous crimes held in the computer's memory banks. When Tony had slipped out of his seat, she'd vaguely registered the movement, but forced herself to carry on working. The last thing she wanted was for him to think she was trying to ingratiate herself.

The intensity of the concentration she imposed upon herself was sufficient for her not to notice when he came back in through the door behind her desk until her subconscious registered a faint masculine smell which it identified as his. It took all her willpower not to react. Instead, she carried on striking keys until his hand cleared the edge of her peripheral vision and placed a carton of coffee topped with a Danish on the desk beside her. "Time for a break?"

So she'd rubbed her eyes and abandoned the screen. "Thanks," she said.

"You're welcome. Anything you're not clear about? I'll take you through it, if you want."

Still she held back. Don't snatch at it, she cautioned herself. She didn't want to use up her credit with Tony Hill until she absolutely had to, and preferably not before she'd been able to offer him something helpful in return. "It's not that I don't understand it," she said.

"It's just that I don't trust it."

Tony smiled, enjoying her defensive stubbornness. "One of those kids who demanded empirical proof that two and two were always going to be four?"

A prick of delight that she'd entertained him, quickly stifled. Shaz moved the Danish and opened the coffee. "I've always been in love with proof. Why do you think I became a cop?"

Tony's smile was lopsided and knowing. "I could speculate. It's quite a proving ground you've chosen here."

"Not really. The ground's already been broken. The Americans have been doing it for so long they've not only got manuals, they've got movies about it. It's just taken us forever to catch on, as per usual. But you're one of the ones who forced the issue, so there's nothing left for us to prove." Shaz took a huge bite of her Danish, nodding in quiet approval as she tasted the apricot glaze on the flaky pastry.

"Don't you believe it," Tony said wryly, moving back to his own terminal. "The backlash has only just started. It's taken long enough to get the police to accept we can provide useful help, but already the media hacks who were treating us profilers like gods a couple of years ago are jumping all over our shortcomings. They oversold us, so now they have to blame us for not living up to a set of expectations they created in the first place."

"I don't know," Shaz said. "The public only remember the big successes.

That case you did in Bradfield last year. The profile was right on the button. The police knew exactly where to go looking when it came to the crunch." Oblivious to the permafrost that had settled over Tony's face, Shaz continued enthusiastically. "Are you going to do a session on that? We've all heard the grapevine version, but there's next to nothing in the literature, even though it's obvious you did a textbook job on the profile."

"We won't be covering that case," he said flatly.

Shaz looked up sharply and realized where her eagerness had beached her.

She'd blown it this time, in spades. "I'm sorry," she said quietly. "I get carried away, and tact and diplomacy, they're history. I wasn't thinking." Thick git, she berated herself silently. If he'd had the therapy he would have needed after that particular nightmare, the last thing he'd want would be to expose the details to avid prurience, even if it was masquerading as legitimate scientific interest.

"You don't have to apologize, Shaz," Tony said wearily. "You're right, it is a key case. The reason we won't be covering it is that I can't talk about it without feeling like a freak. You'll all have to forgive me. Maybe one day you'll catch a case that leaves you feeling the same way. For your sake, I sincerely hope not." He looked down at his Danish as if it were an alien artefact and pushed it to one side, appetite dead as the past was supposed to be.

Shaz wished she could rerun the tape, pick up the conversation at the point where he'd put the coffee down on her desk and there was still the possibility of using the moment to build a bridge. "I'm really sorry, Dr. Hill," she said inadequately.

He looked up and forced a thin smile. "Truly, Shaz, there's no need.

And can we drop the

"Dr. Hill" bit? I meant to bring it up during yesterday's session, but it slipped my mind. I don't want you all feeling that I'm the teacher and you're the class. At the moment, I'm the group leader simply because I've been doing this for a while. Before long, we'll all be working side by side, and there's no point in having barriers between us. So it's Tony from now on in, OK?"

"You got it, Tony." Shaz searched for the message in his eyes and his words and, satisfied it contained genuine forgiveness, wolfed the rest of her Danish and returned to her screen. She couldn't do it while he was here, but next time she was in the computer room alone, she intended to use her Internet access to pull up the newspaper archives and check out all the reports of the Bradfield serial killer case. She'd read most of them at the time, but that had been before she'd met Tony Hill and everything had changed. Now, she had a special interest. By the time she was finished, she'd know enough about Tony Hill's most public profile to write the book that, for reasons she still couldn't understand, had never been written. After all, she was a detective, wasn't she?

Carol Jordan fiddled with the complicated chrome coffee maker, a housewarming present from her brother Michael when she'd moved to Seaford. She'd been luckier than most people caught in the housing market slump. She hadn't had far to look for a buyer for her half of the warehouse flat she and Michael owned; the barrister he'd recently been sharing his bedroom with had been so eager to buy her out that Carol had begun to wonder if she'd been even more of a gooseberry than she'd imagined.

Now she had this low stone cottage on the side of the hill that rose above the estuary almost directly opposite Seaford; a place of her own.

Well, almost, she corrected herself, reminded by the hard skull head-butting her shin. "OK, Nelson," she said, stooping to scratch the black cat's ears. "I hear what you're saying." While the coffee brewed, she scooped out a bowl of cat food to a rapture of purring followed by the sloppy sound of Nelson inhaling his breakfast. She walked through to the living room to enjoy the panorama of the estuary and the improbably slender arc of the suspension bridge. Gazing out across the misty river where the bridge appeared to float without connection to the land, she planned her coming encounter with the fire chief. Nelson walked in, tail erect, and jumped without pause straight on to the window sill where he stretched out, arching his head back towards Carol and demanding affection. Carol stroked his dense fur and said, "I only get one chance to convince this guy that I know arse from elbow, Nelson. I need him on my side. God knows, I need somebody on my side."

Nelson batted her hand with his paw, as if responding directly to her words. Carol swallowed the rest of her coffee and got to her feet in a movement as smooth as the cat's. One of the advantages she'd soon found with a DCI's office hours was that she actually managed to use her gym membership more than once a month, and she was already feeling the benefit in firmer muscle tone and better aerobic fitness. It would have been a bonus to have someone to share it with, but that wasn't why she did it. She did it for herself, because it made her feel good. She took pride in her body, revelling in its strength and mobility.

An hour later, enduring the tour of the central fire station, she

was glad of her fitness as she struggled to keep pace with the long legs of the local chief of operations, Jim Pendlebury. "You seem to be better organized here than CID ever manages," Carol said, as they finally made it to his office. "You'll have to share the secret of your efficiency."

"We've had so much cost-cutting, we've really had to streamline everything we do," he told her. "We used to have all our stations staffed round the clock with a complement of full-time officers, but it really wasn't cost effective. I know a lot of the lads grumbled about it, but a couple of years back we shifted to a mix of part-time and full-time officers. It took a few months to shake down, but it's been a huge advantage to me in management terms."

Carol pulled a face. "Not a solution that would work for us."

Pendlebury shrugged. "I don't know. You could have a core staff who dealt with the routine stuff and a hit squad that you used as and when you needed them."

"That's sort of what we have already," Carol said drily. "The core staff is called the night shift and the hit squad are the day teams.

Unfortunately, it never gets quiet enough to stand any of them down."

With part of her mind, Carol added to her mental profile of the fire chief as they spoke. In conversation, his straight dark eyebrows crinkled and jutted above his blue-grey eyes. Considering how much time he must spend flying a desk, his skin looked surprisingly weathered, the creases round his eyes showing white when he wasn't smiling or frowning.

Probably a part-time sailor or estuary fisherman, she guessed. As he dipped his head to acknowledge something she'd said, she could see a few silver hairs straggling among his dark curls. So, probably a few years the far side of thirty, Carol thought, revising her initial estimate.

She had a habit of analysing new acquaintances in terms of how their description would read on a police bulletin. She'd never actually had to produce a photo fit of someone she'd encountered, but she was confident her practice would have made her the best possible witness for the police artist to work with.

"Now you've seen the operation, I take it you're a bit more willing to accept that when we say a fire's a query arson, we're not talking absolute rubbish?" Pendlebury's tone was light, but his eyes challenged hers.

"I never doubted what you were telling us," she said calmly. "What

I doubted was whether we were taking it as seriously as we should." She snapped open the locks on her briefcase and took out her file. "I'd like to go through the details on these incidents with you, if you can spare me the time."

He cocked his head to one side. "Are you saying what I think you're saying?"

"Now that I've seen the way you run your operation, I can't believe the idea of a serial arsonist hasn't already crossed your mind."

He tugged at the lobe of one ear, sizing her up. Finally, he said, "I was wondering when one of your lot would notice."

Carol breathed out hard through her nose. "It might have been helpful if we'd been given a nudge in the right direction. You are the experts, after all."

"Your predecessor didn't think so," Pendlebury said. He might as well have been commenting on the price of fish. All of the enthusiasm he'd shown earlier for his job had vanished behind an impassive mask, leaving Carol to draw her own conclusions. They didn't make a pretty picture.

She placed the file on Pendlebury's desk and flipped it open. "That was then. This is now. Are you telling me you've got query arsons that predate this one?"

He glanced down at the top sheet in the file and snorted. "How far back would you like to start?"

Tony Hill sat alone at his desk, ostensibly preparing for the following day's seminar with the task force officers. But his thoughts were far away from those details. He was thinking about the psychopathic minds out there, already set in the moulds that would generate pain and misery for people they didn't even know yet.

There had long been a theory among psychologists that discounted the existence of evil, ascribing the worst excesses of the most sociopathic abductors, torturers and killers to a linked series of circumstances and events in their past that culminated in one final stress-laden event that catapulted them over the edge of what civilized society would tolerate. But that had never entirely satisfied Tony. It begged the question of why some people with almost identical backgrounds of abuse and deprivation went on not to become psychopaths but to lead useful, fruitful lives, integrated into society.

Now the scientists were talking about a genetic answer, a fracture in the DNA code that might explain this divergence. Somehow, Tony found that answer too pat. It seemed as much of a cop-out as the old-fashioned notion that some men were simply evil and that was that.

It evaded responsibility in a way he found repugnant.

It was an issue that had always held particular resonance for him. He knew the reason he was so good at what he did. It was because for so many of the steps down the road that his prey had taken, he had walked in their footprints. But at some point he could never quite identify there had come a parting of the ways. Where they became hunters at first hand, he became a hunter at second hand, tracking them down once they had crossed the line. Yet his life still held echoes of theirs.

The fantasies that drove them were about sex and death; his fantasies about sex and death were called profiling. They were chillingly close.

It sometimes seemed chicken and egg to Tony. Had his impotence started because he was afraid the unfettered expression of his sexuality might lead him to violence and death? Or had his knowledge of how often the sexual urge led to killing worked on his body to make him sexually inadequate? He doubted he would ever know. However the circuit worked, it was undeniable that his work had profoundly affected his life.

For no apparent reason, he recalled the spark of uncomplicated enthusiasm he'd seen in Shaz Bowman's eyes. He could remember feeling that way too, before his fascination had been tempered by exposure to the horrors humans could inflict upon each other. Maybe he could use what he knew to give his team better armour than he'd had. If he achieved nothing else with them, that alone would be worthwhile.

In another part of the city, Shaz clicked her mouse button and closed down her software. On autopilot, she switched off her computer and stared unseeingly as the screen faded to black. When she'd decided to explore the resources of the Internet as her first stop on the road to disinterring Tony Hill's past, she'd expected to come across a handful of references and, if she was lucky, a set of cuttings in one of the newspaper archives.

Instead, when she'd input

"Tony, Hill, Bradfield, killer' as key words in the search engine, she'd stumbled upon a dark side treasure trove of references to the case that had put his face on the front pages a year before. There was a grisly handful of websites entirely devoted to serial killers which incorporated Tony's headline case. Elsewhere, journalists and commentators had posted their articles on that specific case on their personal websites. There was even a perverse rogues' gallery, a montage of photographs of the faces of the world's most notorious serial killers. Tony's target, the so-called Queer Killer, featured in more than one guise in the bizarre exhibit.

Shaz had downloaded everything she could find and had spent the rest of the evening reading it. What had started out as an academic exercise to figure out what made Tony Hill tick had left her sick at heart.

The facts were not in dispute. The naked bodies of four men had been dumped in gay cruising areas of Bradfield. The victims had been tortured before death with a cruelty that was almost beyond comprehension. After death, they had been sexually mutilated, washed clean and abandoned like trash.

As a last resort, Tony had been brought in as a consultant, working with Detective Inspector Carol Jordan to develop a profile. They were moving close to their target when hunter became hunted. The killer wanted Tony for a human sacrifice. Captured and trussed, he was on the point of becoming victim number five, the torture engine in place, his body screaming in pain. He was saved in the nick of time not by the arrival of the cavalry but by his own verbal skills, honed over years of working with mentally disturbed offenders. But to claim his life, he'd had to kill his captor.

As she'd read, Shaz's heart had filled with horror, her eyes with tears.

Cursed with enough imagination to create a picture of the hell Tony had lived through, she found herself sucked into the nightmare of that final showdown where the roles of killer and victim were irrevocably reversed.

The scenario made her shudder with fear and trepidation.

How had he begun to live with that? she marvelled. How did he sleep?

How could he close his eyes and not be assailed with images beyond most people's imagination or tolerance? Little wonder that he wasn't prepared to use his own past to teach them how to manage their futures.

The miracle was that he was still willing to practise a craft that must have pushed him to the edge of madness.

And how would she have coped if she'd been the one in his shoes?

Shaz dropped her head into her hands and, for the first time since she'd heard of the task force, asked herself if she hadn't perhaps made a terrible mistake.

Betsy mixed a drink for the journalist. Heavy on the gin, light on the tonic, a quarter of a lemon squeezed so that the tartness of the juice would cut the oily sweetness of the gin and disguise its potency. One of the principal reasons that Micky's image had survived untainted by scandal was Betsy's insistence that they trust no one outside the trio that held their secret close. Suzy Joseph might be all smiles and charm, filling the airy sitting room with the tinkle of her laugh and the smoke from her menthol cigarettes, but she was still a journalist.

Even if she represented the most accommodating and sycophantic of the colour magazines, Betsy knew that among her drinking cronies there would be more than one tabloid hack ready to dip a hand in a pocket for the right piece of gossip. So Suzy would be plied generously with drink today. By the time she came to sit down to lunch with Jacko and Micky, her sharp eyes would be blurred round the edges.

Betsy perched on the arm of a sofa whose squashy cushions engulfed the anorectic ally thin journalist. She could keep an eye on her easily from there, while Suzy would have to make a deliberate and obvious shift of position to get Betsy in her line of sight. That also made it possible for Betsy to signal caution to Micky without being seen. This is such a lovely room," Suzy gushed. "So light, so cool. You don't often see something so tasteful, so elegant, so -appropriate. And believe me, I've been in more of these Holland Park mansions than the local estate agents!" She twisted round awkwardly and said to Betsy in the same tones she'd have used to a waiter, "You have made sure the caterers have all they need?"

Betsy nodded. "Everything's under control. They were delighted with the kitchen."

"I'm sure they were." Suzy was back with Micky, Betsy dismissed again.

"Did you design the dining room yourself, Micky? So stylish! So very, very you\ So perfect for Junket with Joseph." She leaned forward to stub out her cigarette, giving Betsy an unwanted view of a creped cleavage that fake tan and expensive body treatments couldn't entirely disguise.

Being commended on her taste by a woman who could without any indication of shame wear a brash scarlet and black Moschino suit designed for someone twenty years younger and an entirely different shape was a double-edged compliment, Micky felt. But she simply smiled again and said, "Actually, it was mostly Betsy's inspiration. She's the one with the taste round here. I just tell her what I want the ambience to be like, and she sorts it out."

Suzy's reflexive smile held no warmth. Another wasted opening; nothing quotable there, it seemed to say. Before she could try again, Jacko strode into the room, his broad shoulders in their perfect tailoring thrusting forward so he appeared like a flying wedge. He ignored Suzy's fluttering twitters and made straight for Micky, descending upon her with one enveloping arm, hugging her close, though not actually kissing.

"Sweetheart," he said, his professional, public voice carrying the thrum of a cello chord. "I'm sorry I'm late." He half-turned and leaned back against the sofa, giving Suzy the full benefit of his perfectly groomed smile. "You must be Suzy," he said. "We're thrilled to have you here with us today."

Suzy lit up like Christmas. "I'm thrilled to be here," she gushed, her breathy voice losing its veneer and revealing the unmistakable West Midlands intonation she'd devoted herself to burying. The effect Jacko still had on women never ceased to astonish Betsy. He could turn the sourest bitch Barsac sweet. Even the tired cynicism of Suzy Joseph, a woman who had the same relationship to celebrity as beetles to dung, wasn't sufficient armour against his charm. "Junket with Joseph doesn't often give me the chance to spend time with people I genuinely admire," she added.

"Thank you," Jacko said, all smiles. "Betsy, should we be heading through to the dining room?"

She glanced at the clock. "That would be helpful," she said. "The caterer wants to start serving round about now." Jacko jumped to his feet and waited attentively for Micky to get up and move towards the door. He ushered Suzy ahead of him too, turning back to roll his eyes upwards in an expression of bored horror for Betsy's benefit. Stifling a giggle, she followed them to the dining-room door, saw them seated and left them to it. Sometimes there were distinct benefits in not being the official consort, she reminded herself as she settled down with her bread and cheese and The World at One.

There was no such relief for Micky, who had to pretend she didn't even notice Suzy's vapid flirting with her husband. Micky tuned out- the boring ritual dance going on next to her and concentrated on freeing the last morsels of lobster from a claw.

A change in Suzy's tone alerted her that the conversation had shifted a gear. Time for work, Micky realized. "Of course, I've read in the cuttings how you two got together," Suzy was saying, her hand covering Jacko's real one. She wouldn't have been so quick to pat the other, Micky reflected grimly. "But I need to hear it from your own lips."

Here we go, Micky thought. The first part of the recital was always hers. "We met in hospital," she began.

By the middle of the second week, the task force office felt like home to the entire team. It was no accident that all six of the junior officers chosen for the squad were single and unattached, according both to their records and the unofficial background checks that Commander Paul Bishop had pursued in canteens and police clubs up and down the country. Tony had deliberately wanted a group of people who, uprooted from their former lives, would be thrown together and forced to develop team spirit. That at least was something he seemed to have got right, he thought, looking around the seminar room where six heads were bowed over a set of photocopied police files he'd prepared for them.

Already, they had started to form alliances, and so far they'd done well to avoid the personality clashes that could split a group beyond salvaging. Interestingly, the associations were flexible, not fixed in rigid pairs. Although some affinities were stronger than others, there was no attempt to make any of them exclusive.

Shaz was the one exception, as far as Tony could tell. It wasn't that there was a problem between her and the others. It was more that she held herself apart from the easy intimacy that was growing between the rest. She joined in the jokes, took part in the communal brainstorming, but somehow there was always distance between her and her fellows. He sensed in her a passion for success that the rest of the squad lacked.

They were ambitious, no denying that, but with Shaz it went deeper. She was driven, her need burning inside her and consuming any trace of frivolity. She was always first there in the mornings and last out at night, eagerly snatching any opportunity to get Tony to expand on whatever he'd been talking about last. But her very need for success made her correspondingly more vulnerable to failure. What he recognized as a desperate desire for approval was a blade that could be used against her with devastating effect. If she didn't learn to drop her de fences so she could use her empathy, she'd never achieve her potential as a profiler. It was his job to find a way of making her feel she could relax her vigilance without risking too much damage.

At that moment, Shaz looked up, her eyes direct on his. There was no embarrassment, no awkwardness. She simply stared for a moment then returned to what she was reading. It was as if she had raided his memory banks for a missing piece of information and, having found it, had logged off again. Slightly unnerved, Tony cleared his throat. "Four separate incidents of sexual assault and rape. Any comments?"

The group had moved beyond awkward silences and polite hanging back to give others a chance. In what was becoming an established pattern, Leon Jackson dived straight in. "I think the strongest link is in the victims. I read somewhere that serial rapists tend to rape within their own age group, and all these women were in their mid-twenties. Plus they all have short blonde hair and they all took time and trouble to stay fit. You got two joggers, one hockey player, one rower. They all did sports where it wouldn't be hard for a weirdo stalker to watch them without attracting any attention."

"Thanks, Leon. Any other comments?"

Simon, already the devil's advocate designate of the group, weighed in, his Glasgow accent and habit of staring out from under his heavy dark eyebrows multiplying the aggression factor. "You could argue that that's because the kind of woman who indulges in these kind of sports is exactly the sort that's confident enough to be out in risky places on her own, convinced it's never going to happen to her. It could easily be two, three or even four attackers. In which case, bringing in a profiler is going to be a total waste of time."

Shaz shook her head. "It's not just the victims," she stated firmly.

"If you read their evidence, in each case their eyes were covered during the attack. In each case, they mention that their assailant verbally abused them continually while he was actually assaulting them. That's more than sheer coincidence."

Simon wasn't ready to give up. "Come on, Shaz," he protested. "Any bloke who's so powerless he needs to resort to rape to feel good about himself is going to need to talk himself up to it. And as for their eyes being covered there's nothing in common there except with the first and third where he used their own headbands. Look' he waved the papers 'case number two, he pulled her

T-shirt over her head and tied a knot in it. Case number four, the rapist had a roll of packing tape that he wound round her head. Way different." He sat back, a good-natured grin defusing the force of his words.

Tony grinned. The perfectly contrived lead into the next subject.

Thanks, Simon. Today, I'm going to hand out your first assignment, the preamble to which is the beginner's guide to signature versus MO.

Anybody know what I'm talking about?"

Kay Hallam, the other woman on the team, raised her hand half a dozen inches and looked questioningly at Tony. He nodded. She tucked her light brown hair behind her ears in a gesture he'd come to recognize as Kay's keynote mechanism for looking feminine and vulnerable to defuse criticism, particularly when she was about to make a point she was absolutely sure of. "MO is dynamic, signature is static," she said.

"That's one way of putting it," Tony said. "However, it's probably a bit too technical for the plods among us," he added with a grin, pointing his finger one by one at the other five. He pushed back his chair and started moving restlessly round the room as he talked. "MO means modus operandi. Latin. The way of doing. When we use it in a criminal context, we mean the series of actions that the perpetrator committed in the process of achieving his goal, the crime. In the early days of profiling, police officers, and to a large degree psychologists, were very literal about their idea of a serial offender. It was somebody who did pretty much the same things every time to achieve pretty much the same results. Except that they usually showed escalation, moving, say, from assaulting a prostitute to beating a woman's brains out with a hammer.

"As we discovered more, though, we realized we weren't the only ones capable of learning from our mistakes. We were dealing with criminals who were intelligent and imaginative enough to do exactly the same. That meant we had to get our heads round the idea that the MO was something that could change quite drastically from one offence to the next because the offender found that a particular course of action wasn't very effective. So he'd adapt. His first murder could be a strangulation, but maybe our killer feels that took too long, was too noisy, frightened him too much, stressed him rather than allowing him to enjoy his fulfilment. Next time out, he smashes her skull in with a crowbar. Too messy. So number three, he stabs. And the investigators write them off as three separate killings because the MO looks so different.

"What doesn't change is what we call, for the sake of giving it a name, the signature. The sig, for short." Tony stopped pacing and leaned against the window sill. "The sig doesn't change because it's the raison d'etre of the offence. It's what gives the perpetrator his sense of satisfaction.

"So what does this signature consist of? Well, it's all the bits of behaviour that exceed what is actually necessary to commit the crime.

The ritual of the offence. To satisfy the perpetrator, the signature elements have to be acted out every time he goes out on a mission, and they have to be performed in the same style every time. Examples of signature in a killer might be things like: does he strip the victim?

Does he make a neat pile of the victim's clothes? Does he use cosmetics on the victim after death? Is he having sex with the victim postmortem?

Is he performing some kind of ritualistic mutilation like cutting off their breasts or penises or ears?"

Simon looked faintly queasy. Tony wondered how many murder victims he'd seen so far. He would have to grow a thicker skin or else be prepared to put up with the jibes of colleagues who would enjoy watching the profiler lose his lunch over another vitiated victim. "A serial offender must accomplish signature activities to fulfill himself, to make the act meaningful," Tony continued. "It's about meeting a variety of needs to dominate, to inflict pain, to provoke distinct responses, to achieve sexual release. The means can vary, but the end remains constant."

He took a deep breath and tried to keep his mind off the very particular variations he'd seen at first hand. "For a killer whose pleasure comes from inflicting pain and hearing victims scream, it's immaterial whether he ... " his voice faltered as irresistible images climbed into his head. "Whether he ... " They were all looking at him now and he desperately struggled to look momentarily distracted rather than shipwrecked. "Whether he ... ties them up and cuts them, or whether he ... "

"Whether he whips them with wire," Shaz said, her voice casual, her expression reassuring.

"Exactly," Tony said, recovering fast. "Nice to see you've got such a tender imagination, Shaz."

"Typical woman, eh?" Simon said with a grunt of laughter.

Shaz looked faintly embarrassed. Before the joke could escalate, Tony continued. "So you might have two bodies whose physical conditions are very different. But when you examine the scenario, things have been done that were additional to the act of killing and the ultimate gratification has been the same. That's your signature."

He paused, his control firmly in place again, and looked around, checking he was taking them all with him. One of the men looked dubious. "At its most simplistic," he said, ' about petty criminals. You've got a burglar who steals videos. That's all he goes for, just videos, because he's got a fence who gives him a good deal. He robs terraced houses, going in through the back yard. But then he reads in the local paper that the police are warning people about the video thief who comes in through the back yard, and they're setting up neighbourhood watch teams to keep a special eye on back alleys. So he abandons his terraced houses and instead he goes for between-the-wars semis and gets in through the side windows in the downstairs hall. He's changed his MO. But he still only nicks the videos. That's his signature."

The doubter's face cleared. Now he'd grasped it. Gratified, Tony picked up a stack of papers divided into six bundles. "So we have to learn to be inclusive when we're considering the possibility of a serial offender. Think "linking through similarity", rather than "discounting through difference"."

He stood up again and walked around among their work tables, gearing himself up to the crucial part of the session. "Some senior police officers and profilers have a hypothesis that's more confidential than the secrets of the Masonic square," he said, capturing their attention again. "We believe there could be as many as half a dozen undetected serial killers who have been operating in Britain over the past ten years. Some could have claimed upwards of ten victims. Thanks to the motorway network and the historic reluctance of police forces to exchange information, nobody has sat down and made the crucial connections. Once we're up and running, this will be something we'll be considering as and when we have time and staff available to look at it."

Raised eyebrows and muttering filled his momentary pause.

"So what we're doing here is a dummy run," Tony explained. "Thirty missing teenagers. They're all real cases, culled from a dozen forces over the last seven years. You've got a week to examine the cases in your spare time. Then you'll have the chance to present your own theories as to whether any of them have sufficient common factors to give us grounds for suspicion that they might be the work of a serial offender." He handed them each a bundle of photostats, giving them a few moments to flick through.

"I should emphasize that this is merely an exercise," he cautioned them, walking back to his seat. "There's no reason to suppose that any of these girls or lads has been abducted or killed. Some of them may well be dead now, but that's probably got more to do with the attrition of life on the street than foul play. The common factor that links them is that none of these kids were regarded by their families as the kind who would run away. The families all claimed the missing teenagers were happy at home, there had been no serious arguments and there were no significant problems with school. Although one or two of them had some history of involvement with the police or social services, there weren't any current difficulties at the time of the disappearances. However, none of the missing kids subsequently made contact with home. In spite of that, it's likely that most of them made for London and the bright lights."

He took a deep breath and turned to face them. "But there could be another scenario lurking in there. If there is, it'll be our job to find it."

Excitement started like a slow burn in Shaz's gut, powerful enough to dim the memories of what she'd read about Tony's last close encounter with a killer. This was her first chance. If there were undiscovered murder victims out there, she would find them. More than that, she would be their advocate. And their avenger.

Criminals are often caught by accident. He knew that; he'd seen programmes about it on the TV. Dennis Nilsen, killer of fifteen homeless young men, found out because human flesh blocked the drains; Peter Sutcliffe, the Yorkshire Ripper, despatcher of thirteen women, nicked because he'd stolen a set of number plates to disguise his car; Ted Bundy, necrophiliac murderer of as many as forty young women, finally arrested for speeding past a police car at night with no lights.

This knowledge didn't frighten him, but it added an extra fris son to the adrenaline buzz that inevitably accompanied his fire-setting. His motives might be very different from theirs, but the risk was almost as great. The once soft leather driving gloves were always damp with his nervous sweat.

Somewhere around one in the morning, he parked his car in a carefully chosen spot. He never left it on a residential street, understanding the insomnia of the elderly and the late-night revels of the young. Instead, he chose the car parks of DIY stores, the waste ground beside factories, the fore courts of garages closed for the night. Secondhand car pitches were best; nobody noticed an extra car there for an hour or two in the small hours.

He never carried a holdall either, sensing it to be suspicious at that time of night. A policeman spotting him would have no cause to think he'd been out burgling. And even if a bored night-beat bobby fancied the diversion of getting him to turn out his pockets, there wouldn't be much to arouse suspicion. A length of string, an old-fashioned cigarette lighter with a brass case, a packet of cigarettes with two or three missing, a dog-eared book of matches with a couple remaining, yesterday's newspaper, a Swiss Army knife, a crumpled oil-stained handkerchief, a small but powerful torch. If that was grounds for arrest, the cells would be full every night.

He walked the route he'd memorized, staying close to the walls as he moved silently down empty streets, his blank-soled bowling shoes making no sound. After a few minutes, he came to a narrow alley which led to the blind side of a small industrial estate he'd had his eye on for a while. It had originally been a rope works and consisted of a group of four turn-of-the-century brick buildings which had recently been converted to their present uses. An auto electrician's sat next to an upholstery workshop, opposite a plumbing supplier and a bakery that made biscuits from a recipe allegedly as old as the York Mystery plays. He reckoned anyone who got away with charging such ridiculous prices for a poxy packet of gritty biscuits deserved to have their factory razed to the ground, but there wasn't enough flammable material there for his needs.

Tonight, the upholstery workshop was going to go up like a Roman candle.

Later, he'd thrill to the sight of yellow and crimson flames thrusting their long spikes into the plumes of grey and brown smoke billowing up from the blazing cloth and the wooden floors and beams of the elderly building. But for now, he had to get inside.

He'd made his preparations earlier that day, dropping a carrier bag into a rubbish bin by the side door of the workshop. Now he retrieved it and took out the sink plunger and the tube of super glue He walked round the outside of the building until he was outside the toilet window, where he stuck the plunger to the window. He waited a few minutes to be certain the contact adhesive had hardened then he gripped the plunger with both hands, braced himself and gave a sharp tug. The glass broke with a tiny tinkle, the fragments falling on the outside of the window, just as they would if it had exploded from the heat. He tapped the plunger smartly against the wall to shatter the circle of glass, leaving only a thin ring still glued to the rubber. That didn't worry him; there would be no reason for any forensic expert to reconstruct the window and reveal a missing circle of glass at the heart of the shards. That done, he was inside within a few minutes. There was, he knew, no burglar alarm.

He took out the torch and flipped it quickly on and off to check his position, then emerged into the corridor that led along the back of the main work space. At the end, he recalled, were a couple of large cardboard boxes of scrap material that local handicraft hobbyists bought for coppers. No reason for fire investigators to doubt it was a place where workers might hang out for a fly fag.

It was a matter of moments to construct his incendiary device. First he opened up the cigarette lighter and rubbed the string with the wadding which he'd previously saturated with lighter fluid. Then he put the string at the centre of a bundle of half a dozen cigarettes held loosely together with an elastic band. He placed his incendiary so that the string fuse lay along the edge of the nearest cardboard box, then laid the oily handkerchief beside it with some crumpled newspaper. Finally, he lit the cigarettes. They would burn halfway down before the string ignited. That in its turn would take a little while to get the boxes of fabric smouldering. But by the time they'd caught hold, there wouldn't be any stopping his fire. It was going to be some blaze.

He'd been saving this one up, knowing it would be a beauty. Rewarding, in more ways than one.

Betsy checked her watch. Ten minutes more, then she would break up Suzy Joseph's junket with a fictitious appointment for Micky. If Jacko wanted to carry on charming, that was up to him. She suspected he'd rather seize the opportunity to escape. He'd have finished filming the latest Vance's Visit the night before, so he'd be off on one of his charity stints at one of the specialist hospitals where he worked as a volunteer counsellor and support worker. He'd be gone by mid-afternoon, leaving her and Micky to a peaceful house and a weekend alone.