‘If you catch them,’ said a woman’s voice, ‘give them a medal.’

She was standing behind the young man in a wheelchair. For the first time I saw that he was wearing what looked like the remains of a uniform. Green army-issue T-shirt, DPM desert camouflage trousers that hung loosely on prosthetic legs fitted into Asics trainers so unused they could have just come out of the box. As they looked at my warrant card I saw they shared the same brown-eyed, black-haired good looks and the kind of skin that tans easily.

‘DC Wolfe,’ I said. ‘But who are you?’

The woman laughed. At first I had thought they could be twins, but now she seemed to be a few years older than the young man in the wheelchair.

‘You people are unbelievable,’ she said, her mouth tight with bitterness. ‘Mr Din down there is talking about flying his flag over Downing Street and you really want to see our ID?’

Quite a few reporters and photographers were hanging around, most of them at Abu Din’s end of the street. But a couple of them stirred at the sound of the woman’s voice raised in amused disbelief. I gave Edie the nod and she headed them off before they could come our way.

‘This was a crime scene, ma’am,’ I told the woman. And then I waited. She gave me a driving licence.

Piper Maldini, twenty-nine years old.

‘I haven’t got anything,’ the man in the wheelchair said, panic in his voice. Piper Maldini soothed him with a touch of his shoulder. She fished an NHS card out of his rucksack. Philip Maldini, twenty-six.

‘She’s my sister,’ he said.

I gave them back the driving licence and the NHS card. Piper’s hand was still lightly resting on her brother’s shoulder.

‘You’re here every day?’ I said, as gently as I could.

Piper Maldini still took offence. ‘Is that a crime, too?’

I shook my head.

‘Was it the Hanging Club?’ Philip Maldini said, excitedly. He had none of the thin-skinned aggression of his sister. ‘Is that who took him?’

I could give them a bunch of flannel or I could tell them the truth.

‘We’re working on that assumption, although we haven’t ruled out that it could be a group of self-starters.’

‘And he got away?’

‘Yes.’

‘Better luck next time,’ Piper said.

‘Why do you come down here?’ I asked them.

‘To confront the people who would dance on our graves,’ Piper Maldini said. ‘Why do you come down here, Detective? To protect the likes of Abu Din?’

‘I’m just doing my job.’

‘Isn’t that what the guards said at the Nazi concentration camps?’

I stared at her. ‘I don’t think of myself as a concentration camp guard,’ I said. ‘Ma’am.’