It had been sixteen years. Elder had been based in Lincoln, CID, established, not so many months off forty. The big four-O. Katherine was barely two, a toddler, agile enough at night to infiltrate herself between Joanne and himself in their bed. He had noticed Maddy Birch around the station, the odd word exchanged in passing, nodded greetings in the canteen: enough to notice the colour of her eyes, the same shade as Joanne's, the absence of rings on her left hand. Late twenties, he supposed, maybe younger still.

One evening, late, a leaving do for someone in Traffic neither of them really knew, they bumped up against each other in the crush at the bar, her hand resting for a moment on his arm as she steadied herself, the second time surely no mistake. When he'd smiled what was intended as an inviting smile, she'd looked away. Which of them had contrived that they leave together, he was never sure; maybe neither, maybe both. The cobbles on the street outside were slippery and wet, the street narrow and steep. Only natural to reach out a hand, steady her against a fall. Above and behind, lights picked out the west front of the cathedral, the stonework of the castle opposite. His fingers touched her cheek and neck. The doorway into which they half-stumbled, half-stepped was barely deep enough to hold them both. His mouth found hers, her mouth found his. She said his name. Clumsily unbuttoning her coat, his hand closed on her breast. She fumbled with the front of his clothes, gave up, gripped hard instead. The flesh of her neck was warm and soft and when he kissed her there, low in the dip between muscle and bone, she moaned and squeezed tighter and he came, standing there, came against her hand.

Oh, Christ!

She kissed him near the side of his mouth and, after a moment, when she stepped away, there was light enough to see the rueful smile upon her face.

'I'm sorry,' he said.

'Don't be.' Her finger to his lips. And then, 'Come on, let's walk,' linking her arm through his.

At the foot of the hill, they went their separate ways, she a short walk to the place she'd recently bought, he in a taxi to the home where wife and child would doubtless be sleeping, somehow managing to take up, between them, most of the bed.

The central heating had switched itself off automatically and, still wearing his coat, he sat in the kitchen with a glass of Scotch in both hands, taking his mind as slowly as he could through what had happened, moments that were already uncertain, half-imagined.

Neither of them spoke of it again; nothing else happened.

It was the only time, in all the years of his marriage, that Elder had strayed.

Yet he found himself from time to time remembering, images appearing from nowhere, a kaleidoscope of touch and warmth and breath.

And now she was dead.

He read the report again.

Maddy had been at a yoga class that evening and had left alone; it was assumed she'd been attacked shortly afterwards. As yet the police were uncertain as to the exact sequence of events. What was certain was that at some point after finishing her class, getting changed and leaving the centre, Maddy Birch had been attacked, most probably raped, beaten, cut and left for dead.

Elder knew that Robert Framlingham was now based with the Murder Review Unit at Trenchard House; not so many months ago he had been in touch, eager to persuade Elder to join his team of recently retired detectives who were being increasingly used to re-examine cold cases or review investigations that had stalled. As he had with the earlier approach from Nottinghamshire, Elder had politely yet firmly declined.

Framlingham's voice, as ever, was rich and full, unlike the man himself, who was whippet thin and tall enough to make Elder crane his neck when they ever met.

'Frank, changed your mind, I'll be bound.'

'Afraid not,' Elder said.

Framlingham chuckled. 'Well, if it's about a loan…'

'Don't worry, not that.'

'Then shoot.'

'The DS who was murdered at Crouch Hill, Maddy Birch…'

'Not idle curiosity…'

'Not really. I knew her. I mean, we worked together. A while back. Lincolnshire.'

'Personal, then?'

'If you like.'

'What's your interest, Frank? I mean, exactly?'

'I'm not sure. Just wondering who was handling the investigation, how it was going?'

'Not my department, Frank. Not yet. Nothing breaks, they'll bring us in soon enough.'

'There's no one I could talk to, just informally?'

Framlingham seemed to hesitate. 'Let me have your number again, Frank, I'll get back to you.'

When he did, Elder was raking out the ash from the wood-burning stove, prior to setting it for the evening. Not quite dark, the light towards the sea was rimmed with pinkish red. The temperature seemed to have dropped some five degrees.

'I've spoken to the head of the Murder Squad,' Framlingham said. 'Explained the situation. He gave me the name of one of his DCIs. Shields. Karen Shields. Mean anything to you?'

'Can't say that it does.'

'Bumped up to chief inspector a year or so back. Usual bleating by a few, positive discrimination, you know how it goes.'

'You mean because she's a woman?'

'Because she's black.'

'I see.'

'You don't have a problem with that, Frank?'

'God, no.'

'Good.'

'Just as long as she's doing the job.'

'She is.'

'You think it would be okay for me to give her a call?'

'You could try. Say you've had a word with me first, if you think it'll help. If she thinks you might have something useful to throw into the pot, background, that sort of thing, she might be willing to talk.'

'It was a long time ago, Robert.'

'Well, you'll know best. But here's her office number anyhow.'

Elder found a pen and wrote it on the back of his hand.

'And Frank…'

'Yes?'

'You know what I'm going to say, don't you? Any time you do change your mind…'

'Thanks for the number, Robert,' Elder said.

Karen could feel things slipping irrevocably away.

What Vanessa had told them about Maddy's fears that she was being spied upon suggested strongly that her attacker was someone who knew her, knew her well. And Terry Patrick had seemed the obvious candidate. But Patrick's alibis for the night in question had proved near-perfect. Tina aside, five other witnesses were prepared to swear he was in North Wales and not in London.

Stone wall: try again.

So far Forensics had given them little or nothing. No skin beneath the victim's fingernails from where Maddy had sought to fight off her attacker, no saliva, no semen; what resembled a snail's slow trail across her body had proved to be exactly that. The only blood was Maddy's own. All the indications were that she had been raped, penetration had certainly taken place; a condom had presumably been used though one had not had been found, discarded, at or near the scene. Shoe prints and boot prints were too confused, too partial to be of any direct use. Of any possible weapon there was no sign.

The other members of Maddy's yoga class had all been interviewed; Maddy had chatted to one or two of the class before the session started, a few more once it was over, nothing consequential. She had been among the last to leave. The cafe in the centre had closed at seven and there had been few other people still on the premises, all of them tracked down and spoken to. Occupants of the properties backing on to the centre had been canvassed; appeals made for anyone who might have been using the lane or the old railway line as a cut-through or to walk their dogs to come forward.