‘Dr Stephen is going to provide a detailed profile of Bob the Butcher,’ the chief super continued. ‘Then, based on this profile, Ms Bush is going to write a comment piece in the Post designed to tempt Bob into explaining himself in an online interview. And Mr Cho will be waiting to drive a very large hole through his firewall.’

‘Press his buttons,’ said Scarlet Bush. ‘Make Bob stop hiding behind the grandiose Robert Oppenheimer sound bites and raise his head above the parapet.’

Mallory shifted uncomfortably in his seat. ‘You really think he’ll respond if you – what? – insult him in print?’

‘If I do it in the right way,’ Bush said. ‘Bob wouldn’t be preening on a social network site if he wasn’t vain, and if he didn’t want attention, and if he wasn’t a narcissist, and if he didn’t want to justify himself to the world. Not necessarily insults – we have agreed that Dr Stephen will have copy approval – more observations. Just enough that Bob will feel the need to explain himself. Just a little. Just enough.’

A look of disbelief must have passed across my face. Bush stared at me, not smiling now.

‘He’ll talk to me for the same reason that, in the end, they all talk to me,’ she continued. ‘Not because it would be great to hear his side of the story. But because I’m going to tell his story anyway. So he can either have his say or stay quiet and let the world have its say.’

‘That’s the way it works, is it?’ I said.

‘That’s exactly the way it works, detective.’

I turned to Swire.

‘Ma’am, we’re throwing everything we’ve got at this Bob the Butcher and—’

‘And that’s what we’re going to keep throwing until we bury him,’ the chief super responded, cutting me off. She turned to Cho. ‘Colin?’

‘I’m confident that PCeU have the kit to find cracks in whatever encryption systems, anonymisers and onion routers he’s using.’

Swire’s eyes swept across the subdued MIT from West End Central.

‘And then you’re going to bring me his head on a spike,’ she told us.

Mallory was staring bleakly at his SIO policy book. The strength seemed to be visibly draining from him. The chief super had made it sound easy, so it felt like a betrayal when I looked out over St James’s Park and thought – why shouldn’t it work? Trace, interview, eliminate – the TIE process was standard police procedure in any major investigation. Maybe Swire’s plan was for the best. Flush the preening little bastard out from under his digital rock.

Scarlet Bush leaned back in her chair.

‘So, Dr Stephen, what kind of guy is Bob the Butcher?’ she said.