‘The guy’s not stupid. He wouldn’t be sending the messages himself anyway and he’d have made damn sure there’s nothing to link him to them.’

‘I reckon that will apply to every face we put in the frame,’ I said.

‘Exactly. Which is why we have a serious fucking problem. We can’t give in to the absurd demand, but at the same time there’ll be public outrage if more of us are killed. The pressure will be like nothing we’ve ever experienced.’

‘So how do we handle it, guv?’ I said.

He shrugged. ‘We do the only thing we can do and that’s our very best. We drop everything else we’re doing and concentrate on finding the bastard responsible. We question every villain and every snout in London. It’ll mean working in tandem with Resnick and his team and any other division that gets drawn into it. And we do whatever we can to protect ourselves and our families.’

‘That’s a tall order, guv.’

He turned to look at me and his expression caused my stomach to do a swift somersault.

‘Don’t you think I know that, Laura?’ he said, and he didn’t try to disguise the tremor in his voice. ‘Why do you think I’m shitting bricks?’

The Met was used to dealing with the big events, including those appalling atrocities committed by terrorists. But the murder of Dave Prentiss was greeted with total shock and disbelief.

By midnight everyone knew about the threat to his colleagues and their loved ones. Inevitably it was leaked to the media and during the early hours it became part of the blanket coverage on the news channels.

Every member of the task force came into the office and Drummond briefed them on what had happened in Battersea. There was an outpouring of grief, followed by a verbal commitment to hunt down those responsible, whatever the risks. The reaction was predictable because it was all so close to home. But the outward displays of solidarity and determination masked an underlying fear that everybody felt. I could see it in their eyes and hear it in their voices. Indeed, most of the detectives said their loved ones had reacted badly, just as Aidan had.

At the briefing, Drummond announced that marked patrol cars would take up position outside the homes of everyone who had received the death threat. He also said that all potential suspects were to be hauled in for questioning.

But there were so many questions that he couldn’t answer. Like what would happen if the killings continued? What level of protection, if any, would be provided? Would detectives be allowed to resign from the task force and take up other duties? Would the top brass actually consider suspending the organised crime investigations? And what was being done to track down the rat within our midst?