While Brigstocke spoke, Thorne thought about control; the exercise of it. Emily Walker’s killer had been meticulous in his preparation, in waiting to make his move and in the use of the bag to suffocate her. Now, there was every reason to believe that the same man was responsible for the death of Catherine Burke. She too had been discovered at home, with no sign of forced entry, so it seemed likely that he had planned her murder every bit as carefully as Emily Walker’s.

A man who waited and watched and then killed twice in three weeks.

‘So, the investigations into these two killings will proceed separately for the time being,’ Brigstocke said. ‘With as much cooperation between ourselves and the boys in Leicester as is required…’

Thorne felt his mouth go dry. Twice in three weeks… as far as they knew.

‘… and if, as seems likely, they turn out to be linked, then we will have the necessary protocols in place.’

By and large, the briefing was about practicalities from then on, as Brigstocke outlined the way forward. Neither force would want to risk the other screwing up their investigations, so it had been agreed that each would have ‘read only’ access to the other’s HOLMES (Home Office Large Major Enquiry System) account. As the Met team’s office manager, DS Sam Karim would be responsible for all case information inputted into their account and for liaising daily with his opposite number in Leicester.

‘Not a problem,’ Karim said.

‘Especially not if his other half ’s a “she”,’ someone added.

It was a ‘delicate’ situation, Brigstocke said, and ‘potentially fraught’, but he trusted his team could handle it.

If his team needed any more reasons to try to make things work, Brigstocke waited until the end to give them the best one of all. He nodded, then turned to the screen behind him as the lights were flicked off. Many in the room had seen the picture of Emily Walker, but none save Brigstocke and his DIs had seen the photo of Catherine Burke that had been emailed across a few hours earlier.

The pictures had been taken from different angles, but projected next to one another, the similarity was evident… and horrifying. Though the limbs were splayed differently and there was a little more blood in one bag than the other, Thorne guessed that all eyes in the room would be drawn, eventually, to the faces. To the shock and desperation etched into each woman’s chalk-white skin, just visible through plastic fogged with her dying breath.

When he had finished talking, Brigstocke left the lights out and waited for each officer to walk out past the pictures on the screen.

Thorne was the last to leave.

‘They’re nothing like each other physically,’ he said. Brigstocke turned and the two detectives stood in the semi-dark, staring at the screen. ‘So, if we’re looking for a connection, it’s not like he’s got a type.’

‘If it’s the same killer,’ Brigstocke said.

‘You think it might not be?’

‘I’m just saying we don’t know for sure.’

‘Come on, Russell, look at them…’

Brigstocke gave it a few more moments, then turned away, walked across the room and switched the lights back on. ‘The forensics report came in,’ he said. ‘I haven’t had a chance to go through it properly, but they’re confirming that the celluloid fragment is a piece cut out from an X-ray.’ He continued before Thorne could ask the obvious question. ‘No, they don’t know what it is either, but there are some very decent prints on it and they’re not Emily’s. We’ve got DNA, too. Some hairs on her sweater. Might not be the killer’s, of course, but we’ve eliminated the husband, so if our sample matches the one from Catherine Burke…’

‘They’ll match,’ Thorne said.

‘Sounds like you’re counting on it.’

‘He’s got plans, this bloke,’ Thorne said. ‘It’s probably the only way we’re going to catch him.’

‘As long as we do.’

Thorne leaned back against the wall and stared at the dozens of empty chairs. Already the men and women who had just left them would be settling down at computers and picking up phones; doing everything that could reasonably be done. But Thorne was beginning to sense that real progress was going to depend on the man they were after giving them something more to work with.

‘I might be wrong,’ Thorne said. ‘It might be piss-easy. One look at the stuff these Leicester boys have got and everything could get sorted.’

‘Christ, I hope so,’ Brigstocke said.

Thorne hoped so too, but he could not shake the feeling that this was one of those cases where a break would mean another body.

Thorne picked up a takeaway from the Bengal Lancer on his way home. He hadn’t bothered phoning ahead with the order, had looked forward to the cold bottle of Kingfisher, the complimentary poppadoms and the chat with the manager while he was waiting.

Louise was slumped in front of some celebrity ice-skating programme when he got back. She seemed happy enough, a fair way into a bottle of red wine.

‘Every cloud,’ she said. She raised her glass as though she were toasting something. ‘Nice to have a drink again.’

Thorne went through to the kitchen, began dishing up the food. He shouted through to the living room, ‘You should,’ then pushed the empty cartons down into the bin.

When he turned round, Louise was standing in the doorway. ‘Should what?’

‘Should… have a drink… if you want. Relax a bit.’

‘Get pissed, you mean?’

Thorne licked sauce off his fingers, stared at her. ‘I didn’t mean anything, Lou…’

She walked back into the living room and, after a moment, he followed her with the plates. They sat on the floor with their backs against the sofa, eating off their laps. Thorne poured himself what was left of the wine; a little over half a glass.

‘Whoever killed the woman in Finchley,’ he said. ‘Looks like he’s done it before.’

Louise chewed for a few more seconds. ‘That Garvey thing you told me about?’

‘Well, that girl, yeah. She’s not his first.’

‘Shit…’

‘Right, all I need.’

She shrugged, swallowed. ‘Might be exactly what you need.’

The food was as good as always: rogan josh and a creamy mutter paneer; mushroom bhaji, pilau rice and a peshwari nan to share. Louise ate quickly, helping herself to the lion’s share of the bread. Almost done, she moved her fork slowly through the last few grains of yellow rice. ‘Sounds like you’re going to be busy.’

Thorne glanced across, searching in vain for something in her face that might give him a clue as to how she felt about it. He hedged his bets. ‘It’s a hell of a big team, so we’ll have to see.’

‘OK…’

‘Listen, shall I open some more wine?’

‘I really don’t mind.’

Thorne looked again and saw nothing to contradict what she’d said. He carried the plates back to the kitchen and fetched another bottle. They settled down on the sofa and watched TV in silence for a few minutes, Louise laughing more readily than Thorne when a former glamour model went sprawling on the ice. Once the show had finished, Thorne flicked through the channels, finally settling on a repeat of The Wild Geese, a film he had always loved. They watched Richard Burton, Roger Moore and Richard Harris charging about in the African bush, the three just about believable as ageing mercenaries.

‘I talked to Phil,’ Thorne said. ‘I meant to say.’

‘Did you tell him what happened?’

‘I didn’t have to.’ Thorne waited to see if she would pick up on it, say something about having confided in Hendricks about the pregnancy. ‘He said you should call him, you know, if you want to talk.’

‘I spoke to him last night,’ she said.

‘Oh, right.’

‘He was really sweet.’

On the television, Harris was begging Burton to shoot him before he was hacked to death by the enemy, but the shouting and gunfire were little more than background noise.