ordelia sat at Paddy's desk scribbling furiously in her notebook, while Lindsay wandered round the room, smoking and fiddling with the assortment of objects on the mantelpiece. Eventually she headed for the drinks cupboard and poured herself a small whisky. 'You want one?' she asked.

That depends. Are we going out for a meal? And if so, when?'

'Must we go out? I'm just not in the mood tonight for all the palaver of menus and waiters and posing about the wine list. I thought I'd go off in search of an Indian takeaway. Buxton may not be the cosmopolitan centre of the universe, but it must have some kind of fast food apart from fish and chips. Unless you have any other ideas?'

'I was rather hoping we could find a nice little restaurant and splash out a bit.'

'Every day I spend down here is a day when I'm earning precisely zilch. I don't feel much like splashing out. Especially since I've got Paddy on my Presbyterian conscience.'

'My treat, Lindsay. I've got it, we might as well spend it.'

Lindsay looked outraged. 'No way,' she retorted. 'We have to know each other a lot better before I let you pay for me. If you feel the need to go out and spoil yourself, fine. But I'll settle for what fits in with my lifestyle, if it's all the same to you.'

Cordelia looked thunderstruck. 'My God,' she complained, 'You're so bloody self-righteous sometimes. Why the hell don't you just relax? There's no need for all this puritanical shit.'

'What do you mean, puritanical shit? Just because I've always paid my own way and I'm not about to stop now. I've worked hard to keep my independence and I'm not about to throw it away.'

Cordelia shook her head in bewilderment. 'Look, I only offered to buy you dinner, not become your sugar momma. You can let someone buy you a meal without becoming a kept woman, you know.'

Lindsay scowled. 'In my business, you learn quickly that there's no such thing as a free lunch.'

'God, you're impossible. All right, go and get a bloody curry if it makes you feel better. We'll split the cost to salve your conscience.'

Lindsay stormed out, slamming the door behind her. By the time she returned with an assortment of Indian food, she was regretting the scene. She found Cordelia lying on the sofa with a glass of wine, reading one of Sunday's papers, ignoring her return. Lindsay began unpacking the tinfoil containers of chicken, lamb and vegetable curries and rice, and said gruffly, 'I'm sorry. I was out of order.'

Cordelia didn't put the paper down. 'How much do I owe you,' she remarked coldly.

'Look, I said I'm sorry. Let's forget it, eh? Come and eat. Then we can talk about the information we've dug up.'

Cordelia folded the paper and got up. 'Okay,' she said quietly. 'We'll forget it. But don't push your luck, Lindsay. You should have the sense to know I'm not trying to buy my way into your life. You going to behave now?'

Lindsay nodded. She launched straight into her analysis of their current position, eager to re-establish their previous closeness. 'If we look at our original list,' she expounded, 'We can cross off Paddy, of course. And you.'

Cordelia smiled. 'That's very generous of you. But you haven't been able to prove I didn't do it. You're simply reacting on instinct. And that goes for Paddy too.'

'Not entirely,' said Lindsay. 'This crime has to have been premeditated to some extent. The fact that Paddy's duffel-coat toggle came from Longnor proves that. It means that the murderer had decided in advance what the murder method would be. It wasn't just a spontaneous reaction of anger in the music room. Now, Paddy didn't know until dinner was nearly over that she would have any opportunity to be alone with Lorna. After that, she had no chance to go back to Longnor to fetch the toggle.

'Paddy is not a member of the music staff and wasn't directly involved in the plans for the concert. Indeed, if she hadn't been asked by Pamela Overton to look after Lorna, she could reasonably have expected to spend the entire evening sitting with you and me. And there would have been no opportunity for her to go sailing off and commit murder. Also, I think we can rule out any conspiracy theory between Paddy and Pamela Overton. No, if Paddy had been planning to have a go at Lorna, she would have picked a different time and place. She'd have made sure she had some kind of alibi. But this way, she'd have had to go ahead with it knowing she'd be the prime suspect. And Paddy's not daft enough for that.' Cordelia slowly nodded agreement.

Lindsay went on. 'The same argument really applies to you. There is no reason why you should have imagined that any opportunity would arise that evening to kill Lorna. So it's highly unlikely that you'd be wandering around with a garrotte stuffed down your cleavage on the off-chance. Now, I know you're very fit, but I don't think you'd have had time to run to Longnor House and back and still get to the music room in time to kill Lorna. Anyway, in both your case and Paddy's, why go all the way back to Longnor when there were dozens of coats in the cloakrooms in this building, amongst which there must have been the odd duffel coat?'

Lindsay broke off and loaded dahl into her mouth with a chunk of nan bread. Cordelia tasted the lamb curry suspiciously and said grudgingly, 'Not bad, this. Okay, then, Sherlock. Let's have the rest of your reasoning.'

Between mouthfuls, Lindsay continued. 'Up to now, we've rather been looking at this crime as if it had been a completely opportunist exercise. In reality, I think quite a bit of foreknowledge and forward planning was involved. On that basis alone, I'm prepared to exclude you and Paddy. Of the others, I feel strongly that Margaret Macdonald is out of the running. It would have been a completely unnecessary crime for her. As she said to us, her life wouldn't have been destroyed by any revelation Lorna could have made.

'Also, look at the actual nature of this murder. It was a very nasty way to kill someone. There was a lot of hatred in whoever did this. It wasn't done in a simple moment of anger or fear. The crime was vindictive; it had real unpleasantness in it, and a pretty gruesome irony in garrotting her with a cello string. Talk about hoist with your own petard! If Margaret Macdonald was going to kill Lorna, she wouldn't have murdered her like this. Their affair was dead, all passion spent far in the past. Margaret has lived for ages with the risk that Lorna might tell someone what had happened, and she made very sure that she lived a life whereby she could cope with the knowledge of that risk.'

Cordelia frowned and said, 'But look at it this way. Probably the only thing that kept Lorna silent in the past was fear for her own reputation. But now it's become rather fashionable to have had a bijou gay fling, so there was less need for her reticence. Surely the risk must have increased recently, and Margaret Macdonald must have realised that?'

'Not necessarily. I don't think Margaret moves in that kind of world. And besides, why would she take a duffel-coat toggle from Longnor? She wouldn't implicate Paddy, who's supposed to be her best friend here.'

'Ah,' said Cordelia with satisfaction, 'but at that stage she wouldn't have specifically been incriminating Paddy, would she? She would just have been diverting suspicion away from herself in a general sort of way. We've probably got enough of a case against her to cast sufficient doubt on Paddy's guilt to get the charges dropped, don't you think?'

'But if we clear Paddy and don't prove who really did it, people will always assume that it was Paddy. And I don't really think Margaret, if she were the guilty party, would allow that state of affairs to continue.'

Cordelia thought for a moment and gnawed a chicken leg. Then she said, 'You're presuming too much on friendship. I don't think I'd speak out to save a friend if my own freedom were at stake.'

That's very candid of you. And you're probably right. Okay, leave Margaret in the running, but only as a rank outsider. Now, there's James Cartwright. We're cutting it rather fine as regards time, as well as assuming that he had access to a key to the music room. Not that that's a very big assumption, given the amount of work he's done there in the past. From their meeting in the afternoon he could have picked up that she'd be there again later. If we could only place him on the scene, we'd have a damn good case.'

'It would certainly be an excellent choice from the school's point of view.' Cordelia remarked.

That's the least of my worries, to be perfectly blunt,' Lindsay replied with asperity.

'Fair enough, but it would be nice for Paddy to have a job to go back to if we ever manage to get her out of this,' said Cordelia. 'So how do we place him on the scene?'

'I don't know. If I could answer that we'd have a case to put to the police. Cartwright is certainly my favourite on balance. To be honest, I can't really see any of the girls having done it.'

'Even though any one of them might have had motive, means and probably foreknowledge of the opportunity? Be fair, you're being sentimental again. Don't forget that a growing-up process which includes incarceration in a place like this gives a certain hard edge to one's character that most people don't acquire till much later in life. I wouldn't mind betting that young Caroline Barrington has enough guts to have carried out that murder if she had had a mind to,' Cordelia speculated.

'No, no, wrong timing again,' Lindsay parried. 'Caroline might have done it before her parents' divorce, while there was still a chance of salvaging her family. But I can't see her as the vindictive avenger of her father's lost face and her mother's lost pride.'

'Come on, Lindsay, you can't use that as a valid argument against Caroline as a suspect,' complained Cordelia.

'Why not? Look, I believe that we all have the capability to commit at least one murder. Fortunately, the precise set of circumstances never actually come together for the overwhelming majority of us. And since I believe that, I find the only way I can deal with the problems of a crime like this is to look at the psychological probabilities. I simply don't think that Caroline's psychology - in so far as I've seen it at work - matches the facts of this crime. I rule out Caroline, just as I rule out Margaret.'

Cordelia pulled a face. 'I'm still not utterly convinced,' she said.

Lindsay leaned back in her seat, lit a cigarette and continued her lecture. 'I can't say I feel so definite about the other two girls we've seen because I know even less about them than Caroline. But since you've told me not to be sentimental, let's look at them. Of the two, I'd say that Jessica was less likely, but with Sarah only marginally more so. Jessica might have killed out of immediate anguish for her brother, but I don't see her having the nerve for this crime. And I don't believe she really had time to do it. Remember - she'd have had to get the spare key to Music 2 and return it to Margaret Macdonald's room. The first part of the exercise wouldn't necessari¬ly have been awkward, because she probably would have been able to do it in the afternoon. But if Paddy was a few steps away from Margaret Macdonald's room, where Jessica said she was when she found her - and it would have been too risky for Jessica to He about that - then I don't see how such an obtrusive girl, with that mane of red hair, could have got it back unnoticed.

'As far as Sarah is concerned, from what we've seen of her so far, I'd say she might - just might - be capable of this killing. But we've no evidence at all to link her with the crime. Really, the only reason why she should be a suspect - apart from my nasty mind - is that we believe she's lied to the police in her statement about Paddy. But even that isn't certain, since Paddy seems to be suffering from amnesia on the subject.'

'And what about the latest addition to the list?' Cordelia demanded.

'Anthony Barrington. Well, he's in the locality. He comes fairly often, so he knows the layout of the school pretty well. Must do by now. He had a very large axe to grind with Lorna. He's a man of action, too, not the sort who'd sit back calmly and shrug off being crossed. However, there's the difficulty he'd have with the keys and remaining unseen. I suspect we're going to have to engineer a talk with him. Which I don't especially relish.'

Cordelia went through to the kitchen and made coffee. Lindsay followed her and said shamefacedly, 'There's one major problem. I'm committed to working next week in Glasgow. Wednesday to Friday. To be quite blunt, I can't afford not to.'

'I'm sure we can work something out with Pamela Overton if you're losing out by being here,' Cordelia said sympathetically.

'It's not just the money, though obviously that's a major consideration. It's the goodwill. The Clarion's my major source of income right now, and if I don't keep up my availability for shifts, they'll find someone else. There are plenty of hungry freelancers around ready to snap up the holes in the Clarion shift rota. Also, I think I've got a strong chance of getting the next full-time staff job that comes along, and I can't pretend that I wouldn't jump at the chance. So far as this business is concerned, after Tuesday night I'm back on part-time only. Which makes me feel a bit of a shit.'

'That gives us four whole days. We'll see how we get on, and maybe the Clarion will give you more time if you need it. Don't despair yet. I'm sure we can do it. We've got to.'

Later, back at their hotel, Lindsay lay awake, listening to the deep breathing that signaled Cordelia's quick drift into sleep. The endless searchings of her restless mind would not let her drop off. She knew that somewhere there was a key that would unlock the closed book of Lorna's death. But the more she wrestled to find it, the more frustrated she became. After an hour's fitful turning and tossing, she slipped out of bed.

Moving softly, she dressed in jeans and a warm sweater. She searched in her bag till she found Paddy's bunch of keys. Then, by the moonlight, she wrote a note for Cordelia:

If I'm not here when you wake up, I'll be up at the school, probably in Paddy's rooms. Come up and get me in the car. Keys inside the boot. Love you dearly. Lindsay.

She propped the note up against Cordelia's alarm clock and quietly closed the door behind her. She crept downstairs and out into the car park. At the car, she unlocked the boot and took out the heavy walking boots and windproof jacket that she always kept there. She slipped the jacket on, then swapped her trainers for the boots. Finally, she pocketed the Ordnance Survey map, dropped the keys into the boot, closed it and set off.

In the moonlight, she climbed steadily through the wood above the town till she emerged on high moorland at the foot of the Victorian folly Paddy had pointed out to her nearly a week before. She climbed the squat stone tower, blessing the almost full moon that made it possible, and gazed over the landscape. The site had been well chosen. In the moonlight, she could see for miles in all directions. Lindsay unfolded her map and gazed out over the terrain. She soon located her target and set off with regular, easy strides across the darkened landscape. The going was not difficult for it had been a fairly dry autumn and the ground was soft, but not as boggy as she expected moorland to be at this time of year. The only sounds were the occasional owl, the sudden quiet whispering of small animals in the tussocks of rough grass and the distant rumble of the odd car engine.

Forty minutes later, she was striding up the drive of Derbyshire House. It was after two by then, and the only lights visible were the dull glow of corridor night-lights. When she reached the main house, she walked all the way round, pausing several times to study the building. Finally, she let herself in by the door near the kitchens, using Paddy's master key. Once inside, she slipped off her boots and moved silently through the corridors. She climbed the back staircase to the music department, using the tiny pencil torch she always carried in her walking jacket, along with her compass, whistle and Swiss Army knife. She unlocked the door to the music room and closed it behind her.

Slowly she walked all round the room, not focusing on any one detail but letting her eyes and mind absorb everything around her. At the end of her circuit of the room, she sat down on the teacher's chair. She closed her eyes and forced herself to recall the scene she had witnessed when she had arrived in answer to Pamela Overton's ominous summons. Again she conjured up details of the room she had seen then and compared it with what she could see now. Nothing came to mind of any significance at all. She sighed, cursed herself for her incompetence, and got to her feet.

Lindsay locked up the music room behind her and prowled round the rest of the music department. But nothing struck her. She even probed around the recesses of the stage area, but still there was no echo in her mind. In despair, she wandered back down the corridor to the hall.

Then, as she had done on the night of the murder, she paused to stare out of the window to collect her thoughts. Not far away, she could see the lights of the squash courts building site. But everything else was in darkness. Below her was the roof of the kitchen area, with its sturdy iron railings and its tubs of miniature trees. And suddenly, Lindsay knew what her mind had been stubbornly hiding from her for the past six days.