As he climbed on to the bike and waited for a gap in the traffic, he glanced up and saw her waving from her bedroom window. She pressed her face against the glass like a child. He waved back and cycled away, heading for the Hornsey Road, the Emirates Stadium glorious against the grey sky ahead of him.

Greg raised a hand to wave again, in case Alex was still watching.

Unaware of the eyes on him.

On both of them.

Though what was inside their heads remained largely a mystery to Dave Holland, he had seen the way that those directly affected by violent death could seem altered physically. It was as if they had been hollowed out by it; or, as in the case of George Walker, shrunken slightly. Walker was six two or three and thickset, but sitting opposite him in the Interview Room at Colindale station, Holland saw a man who seemed almost slight.

‘Won’t be too much longer,’ Holland said. ‘It really helps us to get everything down on tape, you know?’

The Murder Squad was based five minutes away at the Peel Centre, but the brown, three-storey building that housed the offices was no more than the administrative HQ. While investigations were orchestrated from Becke House, officers needing the use of interview rooms, custody suites or good old-fashioned cells would usually make the short journey up the road to Colindale.

‘Anything I can do,’ Walker said.

Holland nodded. He had no way of knowing what George Walker had sounded like before his wife was murdered, but now even his voice seemed small. ‘So, the day before yesterday, you came home at the usual time?’

‘Twelve forty-five, give or take.’

‘And stayed for an hour or so.’

Walker nodded, then said, ‘Yes, an hour,’ when Holland prompted him to speak for the benefit of the tape. He was a teacher at a school close to where he and his wife lived, and Holland had already established that he came home for lunch every day.

‘School meals not got any better, then?’

‘They’re pretty good actually,’ Walker said. He’d been staring at the tabletop, picking at the edge of it with a thumbnail. Now, he looked up and directly at Holland. ‘I just enjoyed going home.’

‘Wish I could do the same,’ Holland said. ‘The canteen here’s bloody atrocious-’

The door opened and Thorne walked in. Holland announced his entrance for the tape, then paused the recording while Thorne made his apologies to Walker for being late. Walker told him not to worry about it.

‘Traffic’s a nightmare,’ Thorne said.

He had popped into the Whittington en route and caught the tail-end of the Friday morning rush hour. They had finally performed the D and C the previous afternoon but had kept Louise in overnight. She had eaten an enormous breakfast and was in better spirits than at any time since she and Thorne had been told about the miscarriage. Thorne could not explain why, but it had made him oddly nervous.

‘I just want to get home now,’ she had said.

He had told her he would do his best to pick her up at lunchtime, or to let her know if there was a problem.

In the Interview Room, once Thorne had sat down, Holland quickly filled him in on what had been covered so far, and they resumed recording George Walker’s statement.

‘Tell us about when you got back after school,’ Thorne said.

Walker cleared his throat. ‘It just felt wrong the minute I came through the door,’ he said.

‘Wrong?’

‘Different…’

‘This would have been what time?’

‘Just before five,’ Walker said. ‘I run a chess club after school on a Wednesday. Otherwise it would have been earlier.’

Thorne glanced over at Holland, made sure he saw the significance, then nodded to Walker to continue.

‘I caught a whiff of something, which was… the blood, obviously. There was a vase on the floor in the hall, and water everywhere. She must have tried to fight him off, don’t you think?’

‘We’re still trying to put it all together,’ Holland said.

‘So, I was calling Emily’s name out in the hall, and then I walked into the kitchen. Well, you saw it.’

‘And you phoned us straight away, didn’t you?’ Thorne glanced down at his notes, although he knew the time very well. ‘We’ve got the call to the emergency services logged at four fifty-six. You sounded very calm.’

‘Did I? I think I was just in shock.’ Walker shook his head, breathed noisily for ten seconds, then said, ‘I can’t even remember calling.’

‘What about afterwards?’ Thorne asked. ‘Do you remember running out into the street? Knocking on your next-door neighbour’s door and shouting about the blood?’

More shaking of the head. ‘Sort of.’ Walker ’s voice dropped to a whisper. ‘I can’t remember exactly what I said… shouted. I can remember my throat being sore afterwards and not knowing why. I was kneeling down with Emily by then, waiting for someone to come. It seemed to be taking ages, you know?’ The tears were coming now, but Walker did not seem bothered. He casually lowered his head and pushed them away with the heel of his hand when he needed to. ‘I really wanted to touch her,’ he said. ‘I knew I shouldn’t, because it would mess up the evidence or whatever. Seen too many of those TV shows, I think. But I just wanted to hold her hand for a few minutes. To reach inside that bag and tuck her hair behind her ear.’

Holland looked hard at Thorne until he got the nod. ‘Do you want to take a few minutes, Mr Walker?’ He pushed back his chair, mumbled something about finding some tissues.

‘Actually, I think we can leave it there,’ Thorne said.

Walker nodded, the gratitude evident in his eyes before he closed them.

As soon as Holland had stopped the tape, Thorne was out of his chair and moving towards the door. ‘Right, let’s see if we can get you a cab organised.’

Walker rose slowly to his feet. ‘The hardest thing was telling Emily’s dad,’ he said. ‘After what happened to Emily’s mother, I mean.’ He turned to look at Thorne. ‘How bloody unlucky can one family get?’

‘Sorry, I’m not with you,’ Thorne said.

Walker seemed confused. He looked at Holland, who shook his head to indicate that he was every bit as in the dark.

‘Oh, I thought you must have known,’ Walker said. ‘My wife’s mother was murdered herself, fifteen years ago. Emily’s maiden name was Sharpe.’

Thorne could do no more than say ‘sorry’ again. As a matter of course, Emily Walker’s name had been run through the CRIMINT system to see if she had a criminal history, but there was nothing on record. A tragedy in her family’s past would certainly not have been considered relevant criminal intelligence.

Walker was still looking from Thorne to Holland and back, as though he were expecting the name he had mentioned to be recognised. He reached for his jacket and, when he spoke, it was clear he was well used to what he was saying being the end of a conversation.

‘She was one of Raymond Garvey’s.’

They watched Walker ’s taxi pull away, and began walking in the other direction, back towards the Peel Centre. It wasn’t quite ten yet. The morning was mild, but there was the lightest drizzle in the air.

‘I made a call before he came in,’ Holland said. ‘He was back at school by two. Didn’t leave until a quarter to five. I can talk to Hendricks again if you like, double-check to see if he’s sure about the timings.’

‘Don’t bother,’ Thorne said.

They picked up the pace a little in an effort to stay as dry as possible.

‘I was thinking about him going back to school after he’d had his lunch,’ Holland said. ‘Suddenly had this image of the killer watching him leave, marching straight up and ringing the doorbell. Emily opening it, thinking her old man had forgotten something.’

Thorne shook his head. ‘Times still don’t fit.’

‘Just had that image, you know?’