Tartaglia exhaled loudly. 'Well, I hope he's not getting arseholed somewhere. He's supposed to be on call.'

'Do you still have the files on the Watson case?'

'Yes. Dave was supposed to pick them up, but he hasn't had a free moment. They're here, if you want to come over and look at them. I'm not going to bed for a while.'

Half an hour later, Donovan was sitting on the sofa in Tartaglia's flat, flicking through the exhibits file from the Watson case. Tartaglia stood by the window, smoking, and watching her. He was still in his work clothes, but had taken off his jacket and tie and rolled up his sleeves. She had given up smoking a few months back and he had opened the window to let out the smoke. Unfortunately, the icy draught just blew it straight back in and she was beginning to feel quite cold, her fingers a little stiff as she turned the pages.

The list of the items removed from Catherine Watson's flat took up more than ten tightly spaced, typewritten pages, and included the contents of her dustbin and dirty laundry basket, as well as items recovered from the area where her body had originally been found, according to Malcolm Broadbent's account. It looked as though forensics had done a thorough job in gathering up anything of possible interest although, as usual, cost constraints had meant that only the items considered to be of immediate interest had been sent off to the lab for forensic testing. Nowhere in the lengthy list was a poem mentioned.

'Maybe the poem's leading us up the garden path, at least as far as Catherine Watson is concerned,' Donovan said, when she had finished reading through. 'Although, don't you think it's a bit of a coincidence that she was an English lecturer? According to Professor Spicer, the poem's pretty obscure.'

'Did Spicer know Watson, by any chance?'

'No. Spicer's at Birkbeck, while Watson taught at UCL. It's not surprising they never came across one another. I counted nearly forty academics in the English faculty at Birkbeck College alone. Some are full-time, some are part-time and, from what I gather, there's quite a bit of turnover. I imagine UCL's the same. How did you get on with Liz Volpe?'

'We turned up something very interesting.'

She noted his use of the word 'we' and was tempted to ask if he found Liz Volpe attractive, just to see what he would say, although she was pretty sure she knew the answer. He was rarely immune to a good-looking woman, although whether he would do anything about it was another matter. Liz Volpe was not a material witness in the case, but she was sure he wouldn't take the risk.

'A photograph of Rachel Tenison is missing from the flat,' he continued. 'Same as with Catherine Watson. And there's another thing. Here, take a look at this.' He passed her a photocopied sheet which lay on the coffee table. It showed the front and back of what appeared to be a postcard. 'This was sent to Rachel only about six weeks ago.'

Donovan struggled to decipher the writing, eventually piecing it together. 'It's pretty obsessive stuff and in a funny way, it echoes the poem. Whoever wrote this is right, though. The picture does look like her,' she said, glancing up at the photograph on the mantelpiece, wondering why Tartaglia had put it there. With her broad forehead, blonde hair and large, round blue eyes, Rachel Tenison looked like an angel, or like the renaissance Madonna on the front of the postcard. It showed how deceptive appearances could be.

'Where did you find it?'

'It was in one of the books Rachel was reading, by her bed. The forensic team must have missed it somehow. The original's gone over to Questioned Documents to see what they can make of it.'

'The writing's distinctive. Was anything similar found in Catherine Watson's flat?'

He shook his head. 'I looked at the report again before you got here. All her correspondence was gone through very thoroughly at the time of the investigation. Nothing else out of the ordinary came to light, certainly nothing like that.'

He stubbed out his cigarette and slammed the window shut, drawing the wooden shutters across to block out the view of the street. 'I've just spoken to Dave,' he said, sitting down in a chair opposite her. 'One of those pay-as-you-go numbers called her home from within a quarter of a mile of her flat on the Friday night. It also comes up in the frequency analysis as one of the top thirty numbers to dial her home phone in the last three months, sometimes very late at night. The phone was bought just over four months ago.'

'Purchaser traceable?'

'No. And Rachel Tenison's home and office were the only numbers dialled, as though the phone was bought just for that purpose.'

'Someone's been very careful.'

He nodded. 'Have you managed to find the woman who was working in the gallery three months ago? Even if Richard Greville can't remember what day of the week it is, she might know if Rachel was being bothered by someone.'

'She's moved from her previous address. We've been trying to trace her through her national insurance number but it doesn't look as if she's working at the moment. She did some temping after she left the gallery but the agency said she was planning to go off abroad for a few months of travel. Maybe she hasn't come back yet. Nick's trying to trace her parents. Greville seemed to think they live in Surrey.'

'The stuff about the poem's really interesting,' he said, after a moment. 'Where's Simon? We need to talk to him now.'

'He still hasn't called me back.'

He thumped the arm of his chair. 'Damn it. He can't just go AWOL when he feels like it and he should know that. We need his help. He's either in or out, there are no two ways about it.'

She frowned. 'He's going through hell at the moment.'

'And I sympathise, but what are we supposed to do? Wait until he pulls himself together? Two women have been murdered. It's just not good enough.'

She was forced to agree with him but said nothing. Turner was a law unto himself and there was no point leaping to his defence when she had no idea where he was or what he was up to. No doubt he was drowning his sorrows on some lonely bar stool somewhere.

'You know, he should never have married Nina.'

'What's that supposed to mean?'

'Like everything, he didn't think it through.'

'She was pregnant, for God's sake.'

'It still doesn't make it the right thing to do.'

'But he loved her.'

'Maybe,' he said, doubtfully. 'But Nina's the sort of woman who needs someone secure, someone grounded, not someone who's, well...' He gave a dismissive wave of his hand.

'How do you know Nina so well?' she asked, suddenly intrigued, but added hastily, 'Don't tell me-'

'No. Nothing like that,' he replied firmly, catching her eye. 'I took her out once, that's all.'

'I didn't know.'

'Why would you? It wasn't anything, really. We just found ourselves at a loose end after work one evening. We were the last ones left in the bar and we got talking. You know how it is. Neither of us wanted to go straight home so we had a Thai from that place at the back of the Bull's Head.'

'And?'

'And nothing. She was perfectly nice, although a bit intense, that's all, and complicated. I felt sorry for her. It was clear she wasn't happy and some stuff about Simon came out. I think they had split up at that point. Maybe she thought getting married would solve everything, but it rarely does.'

'Where was Simon?'

'I don't know. Anyway, we had a perfectly nice dinner, I saw her home and that was that.'

Donovan looked away, amused at how unaware he was of how a woman might read things differently. She wondered if Nina had felt as detached about it all as he did. However, she could well understand his lack of interest. Nina wasn't his type, as she had begun to define it in her head. From what she could tell, he seemed to be attracted to women who were in some way unavailable, as if he thrived on the challenge or the uncertainty. It was the one area where his usual common sense eluded him.

'Try Simon again, will you, Sam,' he said, with a sigh.

Donovan retrieved her phone from her bag on the floor and dialled Turner's number. The phone rang, but again Turner didn't answer and she was diverted to voicemail. She left another message and hung up.

'It is Friday night, you know. Maybe he has a date.'

'In his state? I doubt it.' He frowned and shook his head in frustration. 'He's no good to us like this, you know. I really don't want to be down on him but he should never have been brought in on the case if he wasn't up to it.'

She nodded slowly. 'Why didn't you say something to Steele right at the start?'

He spread his hands. 'What could I have said? I didn't want to land the poor sod in even more hot water. Although if he screws up our investigation, I'll have his head on a plate.'

He leaned back in his chair and yawned, as though he carried the weight of the world on his shoulders. They sat in silence for a moment, then he got to his feet, as though something had just occurred to him, and went over to the collection of filing boxes by the front door. He dug around in one of them until he produced a DVD.

'What's that?'

'It's the crime scene footage from the Watson murder. I've watched it before but I want to see it again, just in case there's anything we've missed. Do you mind? You don't have to stay if you don't want to. It's pretty distressing.'

'No, I think I should see it too.'

He switched on the TV and put the DVD into the player, then sat down heavily on the sofa next to Donovan. He used the remote control to tab through external shots of a busy street, to views of the house, then to where the camera moved inside the building and into the sitting room of the flat. He let the film play.

'The sitting room's at the front,' he said, as the camera panned slowly over the room, sweeping the furnishings and lingering briefly on the details of each object and piece of furniture. Tartaglia pointed at the screen with the remote. 'This is where Broadbent claimed to have found Catherine Watson's body. As you can see, there are no signs of a struggle.'

'So what happened?'

'Several tiny spots of what turned out to be Watson's blood showed up under ultraviolet. They were on the edge of the carpet and floor, with a few specks low down on the wall beside the fireplace. They were invisible to the naked eye, which is presumably why the killer missed them and didn't try to wipe them away.'

'She was assaulted here and not in the bedroom?'

'That's right. Forensics turned up nothing in there.'

'Why were there only a few specks of blood? From what Simon told me, the attack was really vicious.'

'The theory was that the killer used some sort of ground sheet or mat to cover the area before he assaulted her, which would explain why nothing was found in the centre of the room.'

'So, he came prepared?'

'It looks like it. He also took whatever he used away with him.'

'Do you think Alan Gifford and Simon did a good job?' she asked, as Tartaglia pressed play.

'From what I can tell, yes. That was the conclusion of the review team as well. They couldn't find anything new.'

As the camera travelled along the shelves of a tall, over-filled bookcase, Donovan put her hand on Tartaglia's arm. 'Can you pause it again there? I want to look at her books. I was just wondering if maybe she taught nineteenth-century English Lit., if there's some sort of link to Swinburne.'

She squinted, trying to make out what was written along the spines, but the books were too far away.

'We can get the titles digitally enhanced.'

'Simon should be able to tell us what she was teaching,' she said, giving up, after he had stopped and started the footage several times.

'If he sobers up, you mean.'

She made no comment. There was no point arguing or saying anything else in Turner's defence.

Tartaglia started the film again and the camera panned from the bookcase to the fireplace, focusing on the mantelpiece and taking in a few family photographs, a plant, and the pair of white candlesticks covered in bright red wax, which had melted and spilled onto the mantelshelf.

'What happened there?' she asked.

'Don't you remember? She bought some candles earlier that day, along with wine and food. Judging from the amount of wax, it looks as though they were left burning all night.'

'Poor woman,' she said, with a deep sigh, picturing the unsuspecting Watson planning her evening, the wine, the dinner, the candles, getting dressed and letting in her killer. It made her shiver, thinking how close she herself had come to another, very different killer and how easy it was to be deceived by someone.

Turning back towards the window, the camera rested briefly on a couple of cushions on the floor, then swung sharply around and exited the room as though the man behind it had got bored with the view. Vague shots of a dark, narrow hallway were followed by the tiny bathroom, the kitchen, and the bedroom at the back of the flat. The camera zoomed in first on the bed, then on Catherine Watson's bleached, naked body.

'It's weird,' Donovan said, turning away. 'As you say, there are no signs anywhere of a struggle. She wasn't drugged, was she?'

'No. Nor drunk. She hadn't had more than a glass or two of wine.'

'Do you think she went along with being tied up?'

Tartaglia hit stop and put down the remote. 'She must have done. Which means she trusted whoever it was.'

'It still isn't normal.'

'Maybe he frightened her into it, or threatened her with something if she didn't do what he wanted.'

Donovan shook her head, glancing up again at the photograph of Rachel Tenison on the mantelpiece. 'The simple explanation was that Catherine Watson was into S&M.'

'There's no history of it.'

'Then maybe she had only just acquired the taste for it. She told her sister she was in love with someone. Or maybe she just went along with what he wanted to do because she wanted to please him and she had no idea how far he intended to take it.'

He gazed at her thoughtfully for a moment, then nodded. 'I wonder if you're right. It echoes something Dr Williams said. I'm sure Richard Greville lied to us when he told us he knew nothing about Rachel Tenison's taste for S&M. My feeling is, he was probably responsible for her developing that taste. Unfortunately, it doesn't get us anywhere, and as far as Catherine Watson goes, we'll probably never know the truth. Sometimes I wish I'd never heard of the poor woman.' He got to his feet with a sigh, running his fingers through his hair. 'Do you want a drink?'

She stood up. 'No. I should be heading home.'

'Psychologically, the crimes appear so different,' he said, as though his thoughts were elsewhere. 'Maybe we should just concentrate on Rachel and let Simon, or whoever, worry about the other murder. What does it matter if some journalist threatens to publish a story linking the cases?'

Donovan put on her coat and swung her bag over her shoulder. 'If we can't make any sense out of it, how on earth will he?'

He walked over to the TV, took out the DVD and put it away in the box by the door. 'I spoke to Trevor earlier today,' he said, turning round to face her, rubbing his chin. 'He's always great to bounce stuff off and he talks more sense than anyone. I was hoping he might come up with one of his famous flashes of inspiration.'

'What did he say?' she asked guardedly. Whilst she agreed with him about Trevor Clarke's virtues, privately she thought that, at some point, Tartaglia had to give up his former mentor. Also, it would do Tartaglia no good at all if Carolyn Steele found out that Clarke was still meddling from his sick bed.

'He was fascinated to hear about all of this. He agrees the link's not entirely clear and he thinks Steele's right to keep the two separate for now. But he did have one bloody good idea. He's called in a favour or three and fixed up for me to meet Angela Harper tomorrow.'

'Angela Harper?'

'The psychological profiler on the Watson case.'

'You're joking. A profiler? Next you'll be telling me you're becoming a Muslim.'

His face cracked into a broad grin and he shook his head. 'I'm staying a Catholic for the moment, thanks. But like all Catholics, I'm open-minded.'

'Catholics? Are you kidding? They're the most bigoted-'

He waved her remark away. 'Never mind, Harper's different. She knows her stuff and she's one of the few profilers Trevor's ever had time for.'

'Well, that's certainly saying something. Are you going to tell Carolyn?'