ou should know already. Because we're all supposed to read the stuff that is referred to us by our regional colleagues here in Germany. Just like we're all supposed to read whatever Europol sends us.'

He rolled his eyes back in his head and groaned. 'Yeah, yeah. Look, I skim it, OK?'

'Sure, we all do^ that sometimes. But there's stuff in there that we should be paying attention to. Like a murder five weeks ago in Heidelberg? Ring any bells?'

He frowned. 'Some small-time drug dealer, wasn't it?'

'That was their excuse for handing it on to us. But it was obvious that it wasn't a drugs hit.'

'That'd be why I didn't pay much attention,' The Shark interrupted defensively. 'No interest to us.'

'Murder should always interest a cop. I did read it, Shark. And that's what makes me think that the man who killed in Leiden had done it before in Heidelberg. And he's done it since in Bremen.' She got busy with the mouse and pulled up the Leiden report, then sent a command to the printer to make a hard copy of the file. 'Which is why I am going to earn myself some Brownie points by bringing it to the attention of the boss.' She got to her feet, picking up her coffee, and walked across to the common printer. She gathered together the sheets of paper and waved cheerfully to The Shark. 'Don't let me keep you from Krasic,' she offered as a parting shot.

She found Plesch in her office, going through expenses claims. She gave Petra a grateful smile. 'Petra. Bringing me facts, instead of these fictions, I hope?'

She shrugged and dropped into the chair facing Plesch. 'More speculation than hard fact, I'm afraid.'

'Oh well, never mind. It's still a welcome distraction. What's on your mind?'

She placed the print-outs in front of her boss. 'Europol bulletin this morning. The Dutch police are looking for possible connections to a murder they've got in Leiden. It so happens that I was reviewing unsolved murders last week, in the run-up to this undercover operation. Just to see if there were any we might be looking to connect to Radecki and Krasic. I came across a case in Heidelberg that looked vaguely promising, so I asked them to send me a full report. When I went through it, it was clearly not one of ours. But then when I read the details of the Dutch murder, all the bells started ringing. I checked it out, and there are some very striking points of similarity.'

Plesch picked up the papers and read them, her expression deepening to a frown as she noted the common ground between the two cases. 'Jesus Christ,' she said when she got to the end.

'There's more,' Petra continued. 'There's been another murder in Bremen. I pulled the files on it because it reminded me of the case in Heidelberg. The MO is identical.'

Plesch raised her eyebrows. 'The same weird, fucked-up bastard?'

'Looks like it. So what do we do?'

Plesch shrugged. 'We get on to Heidelberg. It looks like that's Case Zero. They probably haven't read their Europol bulletin out there in the sticks. They'll have to liaise with this Dutch cop through Europol. And talk to the people in Bremen.' She blew a breath out through pursed lips. 'Rather them than me. What a nightmare. All that red tape and diplomacy.'

'Couldn't we keep hold of it?' Petra asked.

'On what basis? It's not organized crime, it's not our remit.'

'We made the connection. We're experts in intelligence analysis. We're used to working with Europol.'

'You're kidding me, right? As if you haven't got enough on your plate with Radecki. Come on, Petra, this isn't our kind of thing, and you know it. Let me call the chief investigator on the case in Heidelberg and set the ball rolling. You've done a good job, spotting this. But you've got to let it go now.'

Before Petra could argue further, the door burst open without ceremony and The Shark stood there, pink-faced and bright-eyed. 'Sorry to butt in, ma'am,' he gabbled. 'But this case that Petra showed me the bulletin about - something's just come in on the Wire. It looks like there's another one. Only in Koln this time.'

Petra had been right about the boat, Carol thought. This was no rich man's party toy. It was a wooden motor launch, perfectly proportioned, with a sloping roofed cabin amidships. Tadeusz told her he'd bought it as a virtual wreck because he'd fallen in love with its sleek clinker-built lines. He'd had it restored to its former glory, and now it was an immaculate museum piece that was as functional as when it had been built in the 19308. Gleaming brasswork and polished mahogany caught the light wherever Carol looked in the small cabin. No space was wasted; the three-sided bench had slots for the table to drop into it, making a narrow double bed. The bulkheads had stowage space built in, using every nook and cranny without adversely affecting the elegant proportions of the compartment.

Above and behind the cabin, a tall, morose man leaned on the wheel, waiting for the word from Tadeusz to cast off. 'He doesn't speak more than two words of English,' Tadeusz had said as he helped her aboard. 'He's a Pole, like me. We're the best sailors in the world, you know.'

'I think we English might want to dispute that,' Carol said.

He inclined his head in rueful acknowledgement. Today, he looked nothing like the serious businessman she'd seen so far. Dressed in jeans and a thick fisherman's jersey, a woollen cap jammed over his hair, he resembled every other waterman she'd seen on the short walk from the car to the boat. Only his hands were a giveaway, smooth and uncalloused by hard work. 'Let me show you my boat,' he insisted, ushering her below. He stood back, waiting for her to take it in.

'She's a beauty,' Carol said, meaning it.

'I suspect she was built for someone quite high up in the Nazi party,' he admitted. 'But I've never researched it. I think I'd rather not know. It might spoil her for me if I knew too much about her past.'

'A bit like a lover, then,' Carol said, her wry smile taking any flirtatiousness out of the remark. The irony of his comment ___^ was not lost on her; that he too made his money from misery seemed blindingly obvious. For Tadeusz to paint himself as higher up the moraltotem pole than the boat's putative original owner was, she thought, repugnant. Such ethical blindness would make it easier for her to play her devious game, however.

'I suppose,' he said, his answering glance amused. 'So, a drink? Then we'll go up on deck and I can play at being a tour guide.' He opened one of the wooden hatches and revealed a tiny fridge containing beer and champagne. 'It's too small for full-sized bottles,' he said apologetically, holding up a half-bottle of Perrier-Jouet. 'This OK?'

A few minutes later, they were sitting on the stern bench, champagne glasses in hand as the helmsman cruised gently out of the Rummelsbergersee into the broad reaches of the River Spree. 'Are we talking business today, or just getting to know each other better?' Carol asked.

'A bit of both. I wanted to show you the city from a different perspective, and I thought maybe you could tell me something more of your plans.'

Carol nodded. 'Sounds good to me.'

The boat swung left and turned into the mouth of a lock.

As they waited to go through, Tadeusz told her tales of the commercial barges. How they'd shifted twenty thousand tonnes of rubble a day during the reconstruction of Potsdamer Platz. How a routine customs inspection had revealed a bargee's dead wife buried in the coal bunker. How the river police were called the duck police.

'You seem to know a lot about life on the waterways,' Carol said as they sailed on through Kreuzberg towards the Tiergarten. The trees that lined the canal were heavy with blossom, lending an air of romance to what was, after all, a commercial transport route.

'A certain amount of my business depends on the waterways,' he said cautiously. 'As you've discovered for yourself, I like to know who I'm dealing with, so I've talked to many schippermen over the years. Having the boat makes it easy for me to be among them for legitimate reasons.'

'Surely you don't cruise all over Europe? It would take ages.'

'Usually I have the boat lifted out of the water and towed to where I want it to be. Then I do a little cruising, and a little business.' He smiled. 'All very unsuspicious, no?'

Very clever,' she acknowledged, pleased that her masquerade was finally beginning to produce some hard information.

He pointed out various landmarks as they continued along the canal and into the River Spree again. As they turned into the Westhafenkanal, Tadeusz waved his arm towards the right bank. 'This is Moabit. Not always the nicest part of Berlin, I'm afraid. There were some rough turf wars here between the Albanians and the Romanians, fighting over who got to run their prostitutes where. Low-life stuff, not the sort of thing that interests business people like us.'

'What interests me is supply and demand,' Carol said. 'You can supply me with what I need, and I can supply the paperwork they're paying for. For a price, of course.'

'Everything has a price.' Tadeusz stood up. 'Time for more champagne,' he said, disappearing below.

Damn, Carol thought. She was fed up with this. Not that he wasn't a charming and entertaining companion, but if she'd wanted a guided tour of Berlin, she could have climbed aboard an open-topped bus. It wasn't easy to sit back and appreciate the architecture when her survival required her never to let her guard drop. She wanted to cut to the chase, because the sooner they got down to business, the sooner this whole operation would be over and she could return to her own life.

Tadeusz returned with another half-bottle of champagne. 'OK. We have a little way to go before the next really scenic bit. So maybe you can tell me what it is you think I can do for you.'

Carol sat up straight, assuming the body language of someone engaged in serious discourse. 'It's more what we can do for each other. Are you going to be straight with me this time, or are you still pretending you don't know what I'm talking about?'

He smiled. Til be honest with you. I did make some preliminary inquiries to see if you were who you claimed to be.'

'As I did with you,' Carol interrupted. 'I wouldn't have made an approach to you if I hadn't taken a long, hard look at your professional pedigree. So, am I the woman I say I am?'

'So far, things have checked out. My associates are still asking around, but I'm someone who sets great store by gut reactions. And I have a good reaction to you, Caroline. You're clearly smart, you're cautious but you can be bold when that is what will get results.'

Carol made a mock salute with her glass. 'Thank you, kind sir. I'm glad to see we operate in the same way. Because, in spite of all the good things I'd heard about you, if I hadn't taken to you on that first meeting, I'd have disappeared into the night and you'd never have seen me again.'

He draped his arm along the stern rail, not quite touching her, but making a statement of physical closeness nevertheless. 'That would have been a pity.'

'It would have cost you a lot of hassle that I can save you,' she said, firmly bringing the conversation back to the purely professional. It didn't hurt her campaign if Radecki started to fall for her, but she had to play hard to get, to keep him at arm's length. She couldn't afford to let romance blossom to a point where it would start to seem odd that she wasn't sleeping with him. Even if she wanted to, which she reminded herself forcibly she did not, it would destroy her mission, devaluing everything she had found out about him and his business. If Radecki could demonstrate that they'd been to bed together, it would be a gift to a defence lawyer, turning her testimony from the reliable evidence of a respected police officer into the bitter revenge of a woman scorned. Besides, it would be utterly unprofessional. And Carol didn't do unprofessional.

'You think so?'

'I know so. You were delivering between twenty and thirty illegal immigrants a month to Colin Osborne. The only trouble was that Colin bullshitted you about what he could actually supply. He didn't have access to the kind of paperwork your customers were paying for. That's why he had to double-cross them before they realized he was bluffing.'

'I didn't know about this,' Tadeusz said.

'I don't suppose you did. This isn't a business where dissatisfied customers turn up at the Customer Services desk asking for their money back,' Carol said acidly. 'Once they were in the hands of the immigration people, they were either deported or stuck in detention centres. There was no way for them to contact whoever they'd paid their money to in the first place. And Colin was always clever enough to make sure the businesses they were working in couldn't be tracked back to his door. He used fake names to rent the premises, he always made sure any stock was cleared out before the raids happened. He didn't even lose the sewing machines. It was a shitty way of doing business.

Tadeusz shrugged. 'I suppose he thought he was doing what he had to to survive.'

'You think so? That's not how I do business. If you're going to work outside the law, you need to be more honest than the straight people.'

He frowned. 'What do you mean?'

'If you operate in the straight world and you don't deliver what you promise, you maybe lose your job or your marriage, but mostly nothing truly terrible happens to you. But if you operate in our world and you let people down, sooner or later it costs you more than you're willing to pay. You sell fake drugs on street corners and you're going to take a beating, either from ripped-off customers or from other dealers. You double-cross your mates on a bank job and you're looking over your shoulder for the rest of your life.

'Take Colin. If he did the dirty on one deal, chances are he did it on others too. And look what happened to him. Head blown off on a dirt track in the middle of the Essex marshes. Now, I don't want that to happen to me, so when I do business with people, I do it honestly. And I expect the same from them.'

Tadeusz had drawn his arm back halfway through her speech. He was looking at her with a strange intensity, as if she was giving voice to his most deeply held beliefs. 'You've obviously thought a lot about this,' he said.

'I'm a survivor,' she said simply.

'I can see that.'

'Look, Tadzio, I'm a smart woman. I could have made a reasonable living in the straight world. But I didn't want to make a reasonable living. I wanted to make a lot of money. Enough money to stop when I was young enough to enjoy it. So I found a way to work outside the system. And I'm bloody good at it. I try not to mix with other criminals unless I have to, I cover my tracks and I deliver on my promises. Now, are we going to do business?'

He shrugged. 'That depends.'

'On what?'

'On who killed Colin Osborne.' He raised his eyebrows.

She hadn't expected that, and she was afraid her face showed how startled she was by the question. 'What do you mean?'

'Colin's death was very opportune for you. And nobody seems to know what exactly happened to him. No one has claimed responsibility. Usually, when one villain takes out another, they're eager to capitalize on it. Respect, fear. You know how it works. So, Caroline, did you kill Colin?'

She didn't know what the right answer was. He could be bluffing. He could know more than he was letting on, and this was a test to see how far she'd go to earn his good opinion. He might want her to be the killer, as evidence that she was prepared to be ruthless. Or he might be put off dealing with her if she claimed the kill, uneasy that her way of dealing with the competition might rebound on him in the worst way. 'Why would I do that?' she stalled.

'To muscle in on his trade.'

She shrugged. 'Why would I need to take that route? All I'd have to do would be to come to you with a better deal. I suspect you could supply enough bodies to keep us both happy.'

'You didn't, though, did you? You didn't come near me till Colin was well out of the way.' There was a hard edge to his voice now, and his eyes had lost their warmth. 'That makes me suspicious, Caroline. That, and the fact you look so like Katerina. OK, Colin never met Katerina. But if he was halfway good at what he did, he would have checked me out He would have seen photographs of Katerina at least. And then, when she died, maybe he thought this was the chance to set "up some kind of sting using you to get to me. Only, you decided to eliminate the middle man.'

Carol was unnerved. He was wrong in almost every detail, but he was wrong in the right sort of way. Suddenly, they'd shifted from easy companionship to the edgy realm of suspicion. She didn't know what to do.

She set her glass down and stepped away from him, folding her arms across her chest. 'Let me off this boat.'

He frowned. 'What?'

'I don't have to listen to this shit. I came here in good faith to do business. I'm not going to stand here and take accusations of murder and conspiracy from you. Tell your man to let me off this boat, now. Unless you want me to start screaming?'

Tadeusz looked amused. 'You're overreacting.'

Carol let the flare of anger show in her face. 'Don't you dare patronize me. You're just another gangster, Tadzio. You've got no right to come the moral high ground with me. I don't have to account for anything to you. And I certainly don't want to do business with somebody who thinks I do. This is a waste of my precious time. Now let me off the boat, please.'

He took a step back, clearly unsettled by the vehemence of her reaction. He said something to the helmsman, and the boat veered towards a narrow wharf where a couple of launches were moored. 'Caroline, I didn't mean to offend you,' he said as she moved to the side of the boat nearest the wharf.

'And that's supposed to make me feel better?' The boat pulled alongside and, without waiting for the helmsman to tie up, Carol jumped ashore. 'Don't call,' she threw over her shoulder as she marched up the wharf towards a flight of stone steps. Her whole body was trembling as she reached street level. She checked that he wasn't following her, then stepped to the kerb to hail a cab.

She hoped she hadn't wrecked the operation. But she hadn't been able to think of anything else to do. His suspicions had come out of a blue sky, and she'd allowed herself to sink into complacency, so she hadn't been quick enough on her feet to talk him round. She sank back into the cab seat and prayed she'd got it right.

The small plane from Bremen to Berlin was configured with a single seat on one side of the aisle, which meant Tony could look with impunity at the crime scene pictures Berndt had handed him at police headquarters in Bremen. He took them /(Jut of the envelope with some trepidation. He wasn't looking forward to seeing the mutilated corpse of a woman he had been acquainted with. There was always something bizarrely intimate about poring over photographs of the dead, and he didn't want such familiarity with someone he had known in life.

In the event, it wasn't as bad as he had anticipated. The harsh glare of the flash had made the images of Margarethe's body impossible to connect with the lively woman he remembered. He studied the photos in detail, wishing he had brought a magnifying lens with him. To the naked eye, there seemed to be no significant differences between the body of Margarethe and Geronimo's other victims. They were all laid out in similar fashion, their clothes cut away to form an improbable table cover beneath them, the incongruous wound left by the scalping almost identical.

He was about to give up his perusal of the photographs when something caught his eye. There was something odd about one of the ligatures that bound Margarethe's limbs to the table legs. He peered harder, trying to make out the details. The knot looked different from the others.

Tony felt a faint surge of excitement. It might not seem much but, at this stage of an investigation, any deviation from the pattern carried potentially huge significance. And in this instance, it could be all the more important because this was the crime that had been interrupted. Under the stress provoked by that intrusion, Geronimo might have let his guard slip enough to provide a chink in his boilerplate security system.

He was in a fever of impatience to pick up his laptop and get back to Petra's. Of course, the taxi from Tempelhof seemed to take forever, finding every traffic hold-up in central Berlin. He let himself into the empty flat and made straight for the study and Petra's scanner. While he was waiting for his computer to ready itself, he took out the magnifying glass from his laptop case and studied the picture more closely. He went back through to the dining area and pulled out the other crime scene photographs. A few minutes with the magnifying glass and his heart rejoiced. He'd been right. All the knots on the ligatures appeared to be straightforward, common or garden reef knots, apart from the single exception in that one crucial Bremen photograph.

He returned to the study and plugged the scanner into his laptop's USB port. Minutes later, he was looking at an enlarged and enhanced section of the key picture. Tony knew nothing about knots, only that this one was different from the others. He connected to the internet and linked to a search engine, typing in <knots>. Within seconds, he had a list of websites devoted to the craft of knot-tying. The first site he tried offered him a link to an on-line newsgroup of knot enthusiasts. Tony logged on to the newsgroup and posted a message:

I'm a knot ignoramus, and I need some help in identifying a knot from a photograph, also info on where it's likely to be used and by whom. Is there anyone out there that I can send the pic to as a JPEG file?

It would take at least a few minutes to get a response, always supposing there was a knot anorak on-line at this precise moment. To calm his urgent excitement, Tony went through to the kitchen and made himself a pot of coffee. For the first time in hours, he wondered how Carol was getting on. He remembered their tentative arrangement to meet at some point, but he didn't know when he would be able to get away now he had the bit between his teeth.

When he got back to the desk, he sent her an email, suggesting they meet later that evening. There was a message in his in-box from someone who signed himself Monkey's Fist. Tony knew enough to recognize the name of a particular knot, and he opened the message with a glimmer of hope.

Hi, Knot Newbie. Send me your JPEG and I'll see what I can do.

Within ten minutes, Tony was looking at a second message from his new correspondent.

Easy peasy, Newbie. it's not a common knot, but it's not really outre. This is a Buntline Hitch. It was traditionally used by sailors to tie a line to the bottom of a square sail. It's basically a clove hitch tied around itself. It's more secure than the more common two half hitches, but it has a tendency to jam under pressure. You wanted to know what sort of person would use it, right? Well, like I said, it's a sailor's knot. So I guess they're the most likely people to use one

Tie one on for me. .

Monkey's Fist.

Tony sat back and stared at the screen, his eyebrows lowered in concentration. After a few minutes, he got to his feet and scanned the bookshelves that lined one wall of Petra's study. He found what he was looking for on the bottom shelf, along with other oversized volumes. Tony opened the atlas and thumbed through the pages. But there wasn't enough detail for what he wanted.

Impatient, he turned back to the computer and the search engine. First, he looked at city plans of all the murder sites. Then he studied various physical maps of the countries where the murders had taken place. Finally, he disconnected from the internet and returned to his profile.

8. There is one crucial variation in the murder of Margarethe Schilling. We know the killer was interrupted in the commission of this crime, and any such variations therefore assume great significance since, under stress, we revert to what comes most naturally to us. In this instance, the deviation from pattern takes the form of the knot on the ligature binding the left ankle to the table. All other knots are simple reef knots, involving no specialist knowledge. But the odd one out is a buntline hitch, a relatively uncommon sailor's knot.

It is worth noting that all the cities where the murders were committed have significant access to waterways. Heidelberg and Koln are on major commercial navigable rivers - the Neckar and the Rhine. Although Leiden is no longer a commercial port, it has an extensive canal network at its heart and is close to the convergence of several major routes at Rotterdam. Given my earlier conclusion that our killer can move around Europe with ease, and given his use of a knot that most lay people would have no knowledge of, I'm prepared to go out on a limb here and suggest that it is a strong possibility that the killer is a commercial sailor, perhaps a crew member on a barge. Of course, he may simply be someone with a nautical background who is employed in another area, but I think the combination of factors gives us a strong likelihood of him being a waterman.

Suggested action: I have no idea what records are kept of barge traffic, but I would recommend, if it is possible, that an attempt be made to ascertain whether any particular vessels were in the general area of all of these murders on the relevant dates.

Tony indulged in a moment of satisfaction. He had a good feeling about this. It was, he thought, finally getting somewhere. He didn't know how far Petra and her Dutch friend woul^t be able to take the case, given their limited resources. Rut at least he felt confident that he was pointing them in the right direction. He glanced at his watch. He had no idea when she'd be back, and he was feeling tired and grimy from his day's travelling. He decided to head back to his own apartment, leaving a note for Petra asking her to call him when she had the chance. With luck, they could sit down later and thrash out what he'd gleaned so far. And if the gods were really smiling, she might have news for him too, if the Europol scheme had borne fruit.

Marijke frowned at the notes she'd made. Hartmut Karpf, the detective from Koln, had decided to call her directly as well as sending his initial notes via Europol because there were discrepancies between their two cases that he wanted to discuss. 'I've spoken to my colleagues in Heidelberg and Bremen, and it's not that I doubt we're dealing with the same man,' he'd said. 'But I thought you should know that I think we're looking at a serious escalation here.'

'I appreciate you calling,' she'd said. 'So, what exactly do you have?'

'You want the whole story?' 'Everything you have, from the beginning.' The rustle of paper down the phone, then he spoke. 'OK. Dr Marie-The'rese Calvet, aged forty-six. Senior lecturer in experimental psychology at the University of Koln. She didn't turn up for work this morning, and her secretary couldn't get a reply from her home number. She was due to give a seminar, so one of her colleagues was enlisted to stand in for her. But the slides that accompanied the seminar were locked in Dr Carver's office. So the colleague borrowed the master key from the janitor and let himself into her office. Dr Calvet was lying naked and dead, tied to her desk.' Karpf cleared his throat. 'Her colleague was not exactly helpful. He threw up all over the crime scene.'

'If it's any consolation to you, it probably made no difference. This killer doesn't leave us anything to work with in forensic terms,' Marijke said consolingly.

'I gathered as much. Our scene-of-crime officers were very disgruntled. Anyway, for the record, Dr Calvet's body was on its back, arms and legs spread out, each tied to a leg of the desk near the floor. Four standard reef knots, incidentally. Her clothes were underneath her, they'd been cut away once she was tied down. And it was obvious that her pubic hair had been cut away, along with the skin.'

'So far, this is all according to his pattern,' Marijke said.

'Except of course that this is the first time he has killed someone inside their university,' Karpf corrected her. 'All the other victims were found in their homes.'

'That's true,' Marijke said, mentally kicking herself for her stupidity. But at least now she knew she was dealing with a detective who was as sharp as this inquiry needed. 'What else did you find?'

'I demanded an urgent postmortem. Dr Calvet sustained two blunt trauma head wounds, at least one of which would have been enough to knock her out for a while. There were bruises to her throat consistent with manual strangulation.'

'That's new,' Marijke confirmed.

'The cause of death, however, was drowning. A tube of some sort had been forced into her throat and water poured down it. As with the other cases, I believe. But the really significant difference here is that Dr Calvet was raped vaginally before she was killed.'

'Oh shit,' Marijke breathed. 'That's bad. That's very bad.'

'I agree. Killing's no longer enough for him.'

There had been little more to say. Marijke had promised to send Karpf a full report on the murder of Pieter de Groot, and he had assured her that all the relevant material from his case would be^ent immediately via Europol. The one thing Marijke hajdh^t shared was what she was going to do next. She opened up her e-mail program and began to compose a message. Escalation could change a profile dramatically. Dr Hill needed to know what she had learned as soon as possible. Marijke might not know much about serial killers, but she did know that when anyone as controlled as this killer appeared to be losing it, life could become very cheap indeed.

The private room looked as if it had been modelled on a nineteenth-century hunting lodge. Wood panelling covered the walls, relieved only by heavy oils of rural landscapes. A stag's head was mounted on one wall, a wild boar's on another, the glass eyes glittering in the candlelight. A log fire blazed at the centre of an inglenook fireplace flanked by a pair of leather club chairs. In the middle of the room was a small circular table, blazing brilliant with crystal and silver and dazzling white napery. But it was all an elegant fake.

A bit like me, Carol couldn't help thinking. She hadn't expected to see Tadeusz again so soon after her abrupt departure from his boat. But within an hour of her return to the apartment, she'd opened her door to a bouquet of flowers so large it completely obscured the delivery woman. The card read, I'm sorry. My manners are atrocious. I'll call you soon please don't hang up. Tadzio. -.

The relief was physical. Her shoulders dropped an&her back muscles unclenched. She hadn't blown it after all. Luckily, the reaction she'd invented had proved to be the correct one to disarm him. When he called, he managed to be graciously apologetic without grovelling. And so she'd agreed to his dinner invitation. She'd have liked to have talked strategy with Tony, but he was out of reach. She'd have to make do with a late-night debrief.

To reach the private room, they'd taken a lift to the seventeenth floor of one of the modern skyscrapers in Potsdamer Platz and walked through the reception area of a modern restaurant. Crossing the threshold had been an entry into another world. Carol couldn't help a bubble of laughter escaping her lips. 'It's absurd,' she said.

Tadeusz beamed with delight. 'I hoped you'd think so. I can't take it seriously, but the food is exceptional, and I think it's an experience one should have at least once.'

They sat by the fire, supplied with champagne by their personal waiter, who left them in peace, pointing out that he could be summoned by pressing a buzzer when they were ready to order dinner. 'I really am sorry about this afternoon. I think your resemblance to Katerina unsettles me. It stops me thinking straight. And of course, in our line of business, paranoia is never far from the surface,' Tadeusz said.

'I won't deny I was angry. I'm not accustomed to being accused of murder,' Carol said, allowing a little acid into her tone.

,, He inclined his head in a regretful nod. 'It's not a good basis for building trust. I feel ashamed of myself, if that's any consolation.'

'Let's try and put it behind us. I promise not to walk out if you promise not to ask if I assassinate my business associates.' She smiled.

'I promise. Perhaps I can demonstrate my good intentions by listening to the details of your proposal?' Tadeusz said.

Carol felt butterflies tumbling in her guts. This was one of the many testing points of the operation, she knew. She took a deep breath and outlined her fictitious business in East Anglia once more. 'In exchange for a roof over their heads and food, they work for me without wages for a year. At the end of that time, they get an Italian passport and their freedom. And that's the deal,' she concluded firmly.

He raised his eyebrows. 'A sort of slavery, then?'

'I prefer to think of it as^flndentured labour,' she said. 'Obviously, I only want adults. I don't want families - kids are no use to me.' Carol marvelled at how easily she was playing the role of the tough businesswoman she was supposed to be. She seemed to be getting in touch with a side of herself that she hadn't realized existed. She wasn't sure how much she liked this cold and calculating person, but it took surprisingly little effort to slip into the personality she'd fixed on for Caroline Jackson.

'I don't traffic in kids.'

Carol raised her eyebrows. 'I had no idea you had such a sentimental streak.'

'It's not out of sentimentality or squeamishness,' he said. 'Kids are harder to control. They're noisy. They cry. And they provoke stupid heroics from the parents. It's better to avoid them. So, if we do make a deal, you can rest assured you won't be getting any kids from me.'

He was talking explicitly now, Carol realized with quiet delight. Somehow, she'd penetrated his defences. It never occurred to her that part of the reason for his candour was that she was on his turf; if she proved to be dangerous, she could be closed down permanently without a trace. Had she thought of this possible consequence, she would never have had the courage to up the stakes as she did. 'I'm glad we understand each other. But before we talk terms and details, -J$ I want to see how you operate. You can sacrifice me any time it suits you with a call to the British authorities. So I need to .be sure that I'm linking up with an outfit that is every bit as * professional as mine.'

It was a challenge, a gauntlet thrown down between them. Tadeusz stared at her long and hard, watching the changing light from the fire play across those features at once both strange and yet as familiar as his own. 'How do I know I can trust you?'

'Like I said. You'll have something on me. I show you mine, you show me yours. Take your time. Don't decide now. Think about it. Sleep on it. Do what you have to do to satisfy yourself that I'm on the level. But if you're not prepared to let me see for myself that you can run a serious operation, I'm not taking a chance on you.'

He looked at her, his face unreadable. Carol wondered if she'd pushed too hard, too fast. Had she lost him before she even had him on the hook? Eventually, his lips curled upwards in a smile. 'I'll see what can be arranged. But for now, let's concentrate on paying our debt to pleasure.'

A surge of pure exhilaration swept through Carol. She was really getting somewhere, and it was a great feeling. She tucked her feet under her in the big leather chair and opened the menu. 'Why not?' she said.

The worst thing about profiling, Tony thought as he read the detailed message from Marijke, was the deaths that he couldn't prevent. His way of working was intense, burrowing under the skin of the perpetrator, finding a meaning in behaviour the rest of the world condemned as monstrous or perverse. It was as if he was conducting a dialogue with the dead that made it possible for him to have some sort of intercourse with the mind of the living killer. That, theoretically, should provide the police with a signpost they could place on their own map of the information they had gathered, a signpost that would point them in the right direction. And so, when another name was added to the roll call of victims, it was impossible not to take it as a measure of personal failure.

It was important, he knew, not to let this profound disappointment erode his confidence in what he had already achieved. There was nothing in what Marijke had told him that undermined any of his previous conclusions. What he had to do now was to analyse the new material and incorporate it into his profile. This was simply an accumulation of more data, not an implicit criticism of his performance nor a marker of failure, he insisted to himself.

He could almost believe it, but not quite. He reread what had happened to Dr Calvet, his mouth tightening as his imagination conjured the scene before his eyes. This tiny, fragile woman, completely unsuspecting, an easy target for Geronimo. Odd, he thought. Most killers would have gone for such an easy target first. But this killer had so much confidence in his abilities that he'd started with much greater challenges. Tony wondered if having been disturbed in Bremen had shaken that confidence enough for him to have deliberately chosen a weaker victim in an attempt to shore up his belief in himself. 'It must have been a shock to you, to have someone walk in on you in the middle of your moment of glory,' he said softly. 'You dealt with it, but it must be preying on your mind. Is that why you killed this one in her office? Did you think there was less chance of being disturbed there in the evening, after everyone had gone home?'

Whatever the answer to that question, the change of venue demonstrated that Geronimo was flexible in certain elements of his crimes. But the rape and the attempted strangulation weren't markers of adaptability. They indicated something quite different. He pulled the laptop towards him and began to type.

Following the murder of Dr Calvet in Koln, he will be in a state of considerable agitation. The first three murders are apparently lacking in any obvious element of sexuality. However, there is invariably a link between serial homicide with ritualistic elements and erotic satisfaction for the killer. That there was no overt indicator of this in the earlier crimes would suggest to me that he was in denial about the sexual component in his actions. The rape of Dr Calvet should not, strictly speaking, be seen as an escalation in his activities. In practical terms, it represents the surfacing of a motivation that has been there from the beginning, albeit suppressed.

What is more significant is that he has allowed this breach in his self-control to occur. I believe this may have come about in part because he was disturbed mid-murder in Bremen. This must have unsettled him to a considerable degree, making him much more nervous when approaching Dr Calvet. I believe he will have shocked himself with his actions in Koln. To maintain his earlier level of denial about the erotic nature of what he was doing, he probably convinced himself he had some kind of altruistic mission. But now he has descended to rape, it will be harder for him to maintain the integrity of that delusion.

What does this mean for detection and prevention?

I believe he will try to kill again very soon, perhaps within a matter of days. He has to restore his vision of himself as some sort of avenging angel or righter of wrongs, to erase this momentary lapse into the behaviour of what he may well see as an 'ordinary' criminal.

If I am right that he is somehow connected to the waterways, then his options may be limited to quite a small geographical area. I believe the time has come when N/n's potential targets should be informed of the risks. I would urge that this be done in a low-key manner to avoid alerting the killer. Officers should identify university departments with an experimental psychology specialism and make personal visits to the campuses. They should stress the importance of maintaining confidentiality if they are to have the best chance of capturing the killer, and they should invite co-operation. Lecturers who have been contacted about interviews for a new online magazine should be identified. This could allow a sting to be set up. If this is done quickly, it may prevent a fifth killing.

Tony read over what he'd written, then sent it to Marijke and Petra, with a copy to Carol. From what Marijke had told him, it looked as if the cases were already getting bogged down in red tape, with everything being routed through a secure area in the Europol computing centre at Den Haag. He hoped that, between them, they could inject a sense of urgency into the investigation. Otherwise, they were all going to end up with more blood on their hands.

Tadeusz walked Carol to the door of the apartment block. 'Thanks,' she said. 'It's been an interesting evening.'

He took her hand and bowed deeply over it, planting a kiss on the back of her hand. 'Thank you for coming. I'll call you, yes?'