When she had stayed with him in Cornwall, Katherine had teased him about the way in which, having drank nothing but tea for years, he had become a real coffee snob. Well, he had reasoned, there were worse things to be snobbish about.

Back at the flat, he spooned coffee into a plain white china jug, and, while it was standing, cracked the seal on the Jameson's and poured himself a small glass. Reading through the files, he could see why Maddy Birch's former husband, Terry Patrick, had looked such an almost irresistible suspect, and he could read Karen Shields's anger and disappointment between the lines. Not only had Patrick seemed picture perfect, he was, after so many hours of effort, the only serious suspect she had.

Cross-checking the records of the Sex Offenders Register and the National Criminal Intelligence Service, the computer had flagged some twenty names, all but three of whom had so far been checked and eliminated. Elder wondered how many of these warranted looking at again.

As for the forensics, he couldn't think of many cases he'd worked on where the evidence had amounted to so little. No blood save for the victim's own. No stray hair, no shred of skin. It was hard to believe: so hard it had to be worth persuading Forensic Services to look again, re-examine the clothes and the body.

And he wanted to talk to – who was it? – sliding his glass to one side, he fumbled through his notes – Vanessa Taylor, Maddy's best friend. Maybe this guy, as well. The roofer. Kensit? Kendrick? Kennet. Came over as so reasonable on the tape, talking about the times Maddy had stood him up at the last moment, evenings cancelled whenever she had been thrown some unexpected overtime. Like a south London boy who'd somewhere picked up a few lessons in gender and the negotiation of personal space. Elder slipped the headphones free. Maybe Kennet had never been that involved, not enough to really care. Maybe he was just a nice bloke. There were still some around.

Stretching, Elder walked to the window. The tail lights of vehicles sparkled and blurred as they moved in slow procession towards Finchley Lane, the Great North Way, the M1. Men and women, mostly men, hurried home from the station, backs bowed, heads bent into the wind. Here and there, umbrellas sprouted; spots of rain against the glass. He should phone Joanne and tell her where he was, let her have this number just in case. In case of what?

Dad, I'm never going to be like I was before.

On impulse, he called Maureen Prior first.

He and Maureen had worked closely together for three years in Nottinghamshire, right up to the time of his retirement, and then again last year, when Katherine had been abducted. As an officer, she was efficient and perceptive; her judgement fair but unyielding. At work, she was intolerant of fools, time-servers, anyone who stepped outside the line. But as a person, as a woman, Elder knew next to nothing about her. She had never divulged anything about her private life and all of the speculation that usually arose round unmarried women officers had simply evaporated away. Elder knew where she lived and nothing more: he had never been invited past the front door.

'I thought you'd turned your back on all that,' Maureen said, when he outlined what he was doing in London.

'So I had.'

'But this was different?'

'Something like that.'

'I'd like to think you'd do the same for me, Frank, if the circumstances were the same.'

'What's that?'

'Saddle up that white horse of yours and ride up out of the west.'

'Bollocks, Maureen.'

She laughed, a low chuckle. 'Hope you'll be all right, Frank. Working with a woman.'

'Shouldn't I be?'

'Depends.'

'I worked with you.'

She laughed again, more open this time. 'That was easy, Frank. You scarcely thought of me as a woman at all.'

Joanne, when he spoke to her, was taciturn, distracted, her mind elsewhere.

'How's Katherine?'

'Oh, you know, much the same.'

'I don't suppose she's there?'

He could hear voices, muffled, Joanne with her hand, he imagined, not quite covering the phone.

'No, Frank, I'm sorry, no.'

Which, in the circumstances, probably meant yes. Joanne currying favour. He didn't push it.

They exchanged a few words about Christmas, Joanne's plans for New Year's Eve, and that was that. As soon as the call was over, suddenly hungry, Elder made himself bacon and eggs, slices of soft white bread buttered and folded over, more coffee. Switching on the radio, he worked his way through the pre-sets: a low rumble from down near the bootstraps which the DJ informed him came from the late, great Johnny Cash; something languidly classical; someone with a faint Scottish accent explaining the intricacies of European Union budgeting; fevered commentary on Coventry versus West Ham; a jolt of violent, acerbic sound, like the contents of an old-fashioned kitchen being demolished around someone playing electric guitar – the thrash metal he'd read about somewhere?

Opting for the orchestral concert, he angled his legs round on the settee. Maddy's killer: had she known him or had she been taken by surprise? Opening the envelope, he looked at the photographs of the wounds. Vicious and deep. Vicious and yet whoever had delivered them had retained a degree of control, of calm; calm enough not to have left any apparent clues, to have taken scrupulous care. Controlled anger: anger and control.

Training, then?

Elder closed his eyes.

Army? SAS?

Under the wash of music, he drifted off.

All that coffee, he thought, waking fifteen minutes later to the sound of the announcer's voice and bright applause, how could I fall asleep?

He tried the TV. On one channel, a disparate group of men and women were clambering their way, laboriously, through the jungle; on another, the same people, or others that looked just like them, were sitting around on settees, not speaking, doing nothing at all. So easy to switch off.

The volume of traffic had eased back. High up where he was, he could see the strange, muted glow thrown up by the city, a false, unchanging day for night. Back down in Cornwall the sky would be close to black and scored through with stars, Cassiopeia, Pegasus, the Plough.

He pictured Maddy walking – running? – though a dark space he had not yet seen, except in photographs. The movement of branches in the wind. Foxes following a trail across back gardens; the cry, unworldly, of cats on heat. Clouds across the moon.

Something moving in the thickets of shrub and bush down by the old railway line.

A voice.

Did he call out?

Maddy. Her name.

Trying to conjure up her face as she turned towards the sound, Elder could only see her eyes picked out green in the shadow of the cathedral light, her mouth broadening into a smile and then closing round his in a kiss.

You didn't have her, Frank. Just wanted to… But somehow you let her get stuck inside your head.

Freeing the cord from the hook around which it had been looped, Elder lowered the blind. Another small whiskey before turning in. The sheets unwelcoming and cold. After catnapping as he had, he thought it would be hard to get to sleep, but not so. A few small shifts of position and the next thing he knew he was stretching awake by habit, the hands on his watch showing six o'clock.