'Yeah, from what I saw, they look similar,' Turner said grudgingly. 'Although I didn't get a good look.'

'She's obviously not doing it to herself,' Tartaglia said sharply. 'And you told me she was shit scared. But whether Jennings had anything to do with the Holland Park murder's another question. He denies ever having met Rachel Tenison and we have nothing to say that he's lying.' He glanced over at Turner, half-expecting to be contradicted, but Turner's face was without expression, as though his thoughts were elsewhere.

'Let's leave the Holland Park murder out of it for now,' Steele said, blowing her nose loudly again. 'We haven't got even a whiff of anything against him there.' She took a crumpled pack of Day Nurse out of her bag, popped a couple of capsules in her mouth and washed them down with water. 'Any news from Jennings's flat?'

'The search team is finishing up now,' Tartaglia said. 'But no joy.'

'What about the papers from Catherine Watson's flat?'

'We're waiting on the lab. Tomorrow's the earliest we can expect to hear back.'

Steele shivered and pulled her coat even more tightly around her shoulders. 'Well, unless I ask for an extension, and I'm not sure how the powers that be will like that, we've got twenty-four hours from the time he was brought in here. That gives us until roughly six p.m. tomorrow. Then Jennings walks. We've got to come up with something else fast. Any ideas?'

Tartaglia nodded slowly. 'Watching Jennings just now, I kept thinking of how he behaved when we arrested him. His reaction was quite extraordinary.'

Turner raised his eyebrows. 'Violent, you mean. Shows he's guilty.'

'I'm inclined to agree,' Steele said. 'An innocent man doesn't usually pull a knife unless he's crazy.'

'Sure, but that wasn't what I meant,' Tartaglia said. 'Even if Jennings is as guilty as hell, it still doesn't make sense to react like that. He's been arrested before and never shown any signs of violence.'

'That's right,' Turner added, with a nod. 'He was gentle as a lamb.'

'But this time's different. I keep asking myself why. He's not stupid. Why did he panic?'

Steele looked at Tartaglia questioningly. 'So, how do you read it?'

'Jennings knows we're looking for him, but he thinks he's safe in that flat. He comes home as usual and finds me and Simon there. He freaks out and gives us all that stuff about being innocent. Then for no reason he pulls the knife. I remember the look in his eyes. He wasn't scared, he was angry. Like someone who's been...' He searched for the right word.

'Trapped?' Turner suggested.

'No,' Tartaglia replied. 'Not trapped in the physical sense. He looked like someone who's worried about being found out. But if he knows there's nothing to find in his flat, why risk everything? He should have been relaxed, let us take him in without a fight, like last time.'

'You're right,' Turner said, nodding again. 'He was desperate. He would've done anything to get out of there.'

'My guess is he's got something really hot, something that's worth trying to stab me to protect. We know it's not in the flat otherwise we would have found it. Again, if he felt secure about the hiding place, he wouldn't have been so worried.'

'Where else have you tried?' Steele asked.

'I sent a team over to his parents' place in Tulse Hill,' Turner said, 'but nothing's turned up. According to his mother, he hasn't been home for at least six months.'

'We should check his keys,' Tartaglia replied. 'You remember what the girlfriend told you, that he didn't like her touching them?'

'I'll take a look,' Turner said. 'The duty sergeant should have them.'

Steele looked at Tartaglia. 'What are you expecting to find?'

'His rape kit, for starters. If he's been using it on the girlfriend, it's got to be somewhere handy. But I'd also put money on his having Watson's photograph. It was never found. It's very likely he took it as a souvenir, so that he could keep the memory fresh and relive the whole experience when he wanted.'

Steele nodded and got to her feet. 'That makes sense. I want everyone who's available to check with Jennings's friends and known associates. Find out if he's asked anyone to keep something for him.'

'I'll also talk to Heather as soon as she comes round,' Tartaglia said.

'If she comes round,' Turner added. 'She looked on her way out, to me.'

Steele gave a loud sniff and picked up her bag. 'What's the latest?'

'She's alive but on the critical list,' Tartaglia replied. 'I sent Jane over to A&E earlier.' Jane Downes was one of two family liaison officers on the murder investigation team and had previously worked for several years for a specialist unit dealing with the victims of rape and domestic violence. 'Jane and Karen will take it in turns at the hospital. They'll call me if there's any news.'

'Good,' Steele said. 'Let's just hope, for all our sakes, that the girl lasts the night.'

'If she comes to, perhaps we can get her to press charges for rape,' Turner said. 'At least that should buy us some more time.'

'No, Simon,' Tartaglia said, firmly. 'That's not good enough. Even if she survives, who knows if she'll be prepared to do that. You said she's terrified of him. I want the bastard charged with murder. I'm banking on finding that photograph.'

30.

Just after eight a.m. the next day, Tartaglia stepped out of the lift onto the tenth floor of the north wing of St Thomas's Hospital. After consulting the large directions board, he followed a series of arrows down a long right-angled corridor towards reception. Pushing open the last set of heavy swing doors, he spotted the short, dumpy figure of Detective Constable Jane Downes. Dressed in a baggy, beige checked trouser suit, with chin-length straight blonde hair and a heavy fringe, she stood, hand on hip, beside the coffee machine, engrossed in conversation with an Asian nurse sitting behind the reception desk.

'There you are, Jane,' he said, coming up behind her.

She swung round. 'Ooh, you gave me such a fright, Sir. I didn't know you were there.' She looked up at him with large, tired, owlish blue eyes and made a bad job of stifling a yawn.

'You been here all night?' he asked, wondering how her husband and three kids felt about it.

She nodded. 'She's been out for the count for most of it. You got here quicker than I expected.'

'Came straight over when I got your message. Where is she?'

'In a private room on this floor. I sweet-talked them into putting her in there temporarily. Luckily the woman in charge was sympathetic when I gave her the bare bones of what had happened and told her we needed to talk to Heather. It's this way.'

With a quick smile over her shoulder at the nurse, she steered Tartaglia past the reception desk towards another set of doors.

'How is she?' he asked, holding one side open for her.

'She'll be fine. Don't know what they gave her, but she only woke up an hour or so ago. That's when I called you.'

He walked with her along the corridor, slowing his pace so she could keep up. 'Have you spoken to her yet?'

'Only for a few minutes. She's still pretty drowsy, and knowing what she's been through and that you were coming over, I didn't want to push it straight away.'

'But you think she'll talk?'

'I don't know. She wasn't very interested in me.'

'You've told her what happened at the flat? That we've arrested Jennings?'

'She certainly heard what I said, although there wasn't much of a reaction.'

'You said they'll discharge her later today. We haven't got much time.'

She sighed. 'I know. I'll see about getting her permission for some photos of her injuries, but she's a long way from pressing charges against him for rape and GBH, if that's what you're hoping for.'

'Well, keep on at her. If we don't turn up anything, we're going to have to let him go.'

'I'll do my best, but when you see her, tread carefully. You're a big, strong-looking man, and particularly intimidating in those leathers.'

'I came on the bike. Shall I go back and change?'

'No. Just be extra gentle. Remember that it was a man who did this to her. And to put up with this sort of abuse, she's probably had a background of male violence in her life. It usually starts early on.' Downes stopped outside a door near the end of the corridor. 'She's in here,' she said, and knocked on the door before pushing it open. Tartaglia followed her inside.

Heather lay propped up in bed attached to a drip. Headphones were clamped to her ears and she was watching GMTV on the television on the opposite wall. Her eyes flicked to Tartaglia and Downes as they came in, then back to the screen. Apart from the areas of bruising around her neck and at her wrists, which had deepened into a violent shade of blackish purple, she still looked incredibly pale. But at least she was alive to tell the story, if only she would trust them.

There being only one chair in the room, Downes went outside to find another while Tartaglia took off his jacket, pulled up the chair beside the bed and sat down. Heather carried on watching the television as though he didn't exist. Looking at her closely, he noticed that her eyes were a light hazel, not grey like Donovan's, and her face was considerably thinner and more angular. The superficial illusion of resemblance receded and he felt strangely relieved. He could see clear thumb-mark bruises on the front of her neck and finger marks on the side; it looked as though Jennings had half-strangled her. They appeared recent, maybe only a couple of days old. The rope marks around her neck and wrists were even clearer now and she had the beginnings of a black eye, which he hadn't noticed before in her bedroom. Even if a good defence brief might try to discredit her, the wounds would speak for themselves. He just hoped she would allow them to take photographs.

After a minute or so of being ignored, he stood up, reached over and gently removed the headphones from her head, as though dealing with a child. She put up no resistance. He used the remote to switch off the TV then sat back down. For a moment she continued to stare at the screen then she folded her arms across her bony chest and slowly turned her gaze to him, looking at him questioningly in a half-focused way.

'My name's Mark,' Tartaglia said. 'Mark Tartaglia. I need your help, Heather.'

She said nothing, still gazing blearily at him.

'I'm here about Michael Jennings.' He spoke slowly and deliberately, letting the words sink in. 'He's done something very bad, very bad indeed. We believe he killed a woman you knew called Catherine Watson.'

'Catherine Watson,' she repeated slowly, as though taking it in. Her voice was sleepy and strangely girlish and nasal.

'Yes. He murdered her. As I said, I need your help.'

'You police?'

He nodded. 'We're holding him somewhere secure, but we need to find out where he keeps his things.'

She looked at him blankly, as though she didn't understand what he meant.

'I've got his keys here.' He pulled the clear plastic bag containing Jennings's bunch of keys out of his zip pocket and held it up for her to see. A chunky silver metal fob dangled from the bunch with some sort of Chinese symbol and he hoped she would recognise it and that it would reassure her that they had Jennings. 'There's one for your flat and one for the front door upstairs, one for his parents' house, one for a padlock...'

'His bike. He has a bike.' She spoke faintly, as though it were an effort.

He smiled, pleased that she had responded. 'That's right. We found it in the coalhole, outside your flat. But there are two others on here.' He shook the bag, trying to hold her attention. 'They look like some sort of padlock keys too but we don't know where they're for. Do you have any ideas?'

She sighed and closed her eyes, as if it was all too much for her.

'Please, Heather. I'm sorry to bother you, but it's very important. We've got to find where he keeps his things.' After a minute or so of silence, he asked, 'Did Michael ever show you a photograph of Catherine Watson? It was in a wooden frame.'

'No,' she said, in a half-whisper, eyes still closed.

'You're sure?' She didn't reply. 'I know what he does to you, Heather,' he said softly. 'I know what he puts you through. I'm not going to ask you to talk about it if you don't want to. But he's a very dangerous man. A sick man. He shouldn't have made you do those things. He needs to be locked away so he can't do it again.'

He waited for a response, but there was none. Maybe, in spite of everything, she still cared for Jennings, although she had been desperate enough for money to turn him in. Perhaps she was so inured to what had happened to her, so numb, that the horror of what he had done to her didn't really register.

'He has a knife more than one. Am I right?'

She opened her eyes and looked down at her hands, rubbing the edge of the sheet gently between her fingers.

'He has a collection of knives; he likes to take them out. They make him feel powerful. He uses them to frighten you, doesn't he? Doesn't he, Heather?'

He waited patiently for some sort of response. A few seconds later, Heather gave an almost imperceptible nod of her head.

Encouraged, he continued, 'I know about the things he uses to secure you, the handcuffs, the plastic ties, the gags and stuff.'

He paused, scanning her gaunt face for some sort of a reaction, but again there was none. There was no point asking her why she had put up with it. Jennings had chosen his victim well. She had sunk so low, she would have put up with anything. It was probably the only thing that had saved her, although at some point Jennings would have tired of her and Tartaglia knew what would have happened. He felt a sudden rush of anger on her behalf. He would nail Jennings, as much for her as for Catherine Watson.

'Please talk to me, Heather. We need to find these things. They're proof of what he does. And we must have that proof so we can put him away for good. He's got to be keeping them somewhere. We didn't find anything in your flat. Does he bring them home with him?'

Tears had started to roll down her face but she made no sound. Instead, she looked away, eyes focusing back on the dead TV screen.

'He must have a bag, or something. You must have noticed.'

Still she said nothing and he wondered if she were frightened that Jennings would know that she had talked and would come to find her.

'You know, Michael tried to use one of his knives on me when we came to arrest him.' He raised his voice a little, hoping to get her attention. Maybe if she knew that he had been in the flat with her it would make a difference. 'Michael attacked me. Tried to stab me in the heart. If I didn't know how to defend myself, he would probably have killed me.' He hit his fist against his chest for emphasis.

Slowly she turned her head and looked at him, surprised, her mouth slightly open. 'You?'

Tartaglia nodded. 'Yes. I was there, with DI Simon Turner. He's the tall blond man you let into the flat. We arrested Michael and I had you brought here. I was very worried about you, Heather.'

She was still looking at him, as though she was struggling to remember. 'They told me...you saved my life. Thank you.' Her voice was so very small and faint, he nearly missed her words. She said it simply, as if she was thanking him for doing something trivial.

He smiled again. 'It's OK. I'm just glad I was there. Look, Heather, we've got nothing to hold Michael. Unless we find something to put him in Catherine Watson's flat, we're going to have to let him go later today.'

She tensed and he saw fear in her eyes.

'You don't want that, do you?'

'No. Please...' She gasped, swallowing hard.

'I don't want that either. Before he killed Catherine Watson, he tied her up and did the same things to her that he's been doing to you. She suffered as you've suffered, but she died. You're lucky he didn't kill you too.' He let the words sink in before adding, 'It's possible he may have killed another woman, just two weeks ago. We've got to put him away. For good. So he can't come back and do it again. Please, please will you think.'

She wiped her eyes and face with the corner of the sheet and stared at him helplessly as though it was beyond her power to remember anything.

He had to keep trying. 'I think one of the reasons he was so desperate to get away and why he attacked me is because he's got something which might incriminate him. He's afraid that if we look before he has a chance to hide whatever it is, we might find it. Is this making sense? Where could he be keeping his stuff, the things he uses on you? Who does he see? Where does he go, when you're not with him?'