‘Not necessarily, although it’s a possibility. I think that at least one of them has some kind of specialist training in upholding social control. And I believe that probably more than one of them has experience of some kind of public service. Someone with experience of an institution that sanctions those who violate laws or harm the state. Someone who has been disappointed in the limits and failures and compromises of that institution. So a serving or ex-police officer is one possibility. But equally we could be looking at one or more unsubs who has experience in the prison service or some other branch of criminal justice.’

As I watched Dr Joe thinking I knew what he was going to say next, and I had to stop myself from saying it out loud, from blurting it out, as into my mind leapt the image of my oldest friend and his gap-toothed grin.

‘Or even the military,’ Dr Joe said.

My phone began to vibrate.

The woman on the other end of the phone was crying and apologising all at once. It took me a moment to realise that it was Alice Goddard, the widow of Steve Goddard, kicked to death outside his own home.

‘I’m sorry to call you, Max, I didn’t know who else I could call . . .’

‘Slow down. Take a breath. What’s wrong?’ I said.

But all she could do was to keep apologising and crying.

In my line of work, we move on. There’s always the next case, there is always some fresh human misery coming down the line. But the victims of crime, they don’t move on. They can’t move on. They remain forever stuck in the moment that their life changed, the shock and the pain never diminishing with time. And beyond all the grief that never dies, there can be practical problems. When justice is done, there is usually someone out there raving about the injustice of it all.

The three pieces of pond life who killed Steve Goddard all had friends and families. And sometimes, after pond life has been locked up, these friends and families feel they have a point to prove and a debt to settle.

It can take the form of low-level harassment. It can be petrol poured through a letterbox. It can be anything in between. That’s why I had given Alice Goddard my card and told her that she could call me any time. If the friends and loved ones of the pond life came calling, then I wanted to know about it.

But this was something else.

‘It’s my son,’ she said, her voice breaking.