‘Establish the other side of our perimeter at the far end of the tunnel,’ she told Edie.

‘Ma’am,’ Edie said, and disappeared back inside Dead Man’s Walk.

‘Shall I tell the Crime Scene Manager to send them in?’ I said.

‘Give me a minute,’ Whitestone said.

I knew that every SIO valued this first look. For all our stepping plates and bunny suits and blue gloves, once we started work, this place would never look the same again.

‘So nobody knows this place is down here?’ she said. ‘That’s hard to believe.’

‘It’s not preserved,’ I said. ‘It’s just here – the holding cell, Dead Man’s Walk. Like the cells in the pub across the street. There’s no conservation order on it. There’s no blue plaque outside. It has just survived, by some fluke of history. It’s not open to tourists. It’s not open to anyone. I doubt if more than 1 per cent of the staff of the Central Criminal Court have ever been down here, or even know it exists. One day they’ll replace that boiler room outside and it will all be swept away with no fuss and no ceremony. And nobody will be sorry to see it go because nobody was ever proud of Newgate. Not now. Not ever. Just the opposite. From the time Charles Dickens came to Newgate in 1836, it was a source of national shame.’

‘It’s the perfect kill site. You can smell death in the air. How many hanged at Newgate?’

‘One thousand, one hundred and sixty-nine – not including Mahmud Irani, Hector Welles and Darren Donovan.’

‘Do we know how Wozniak accessed this place from the street?’

‘I’ve asked the search teams to work their way through all the underground car parks of the surrounding office blocks. It might take a while, but they’ll find it.’

‘You’ve carried this investigation, Max,’ she said.

She was staring down at a smear of blood on the floor. It was next to a scrap of torn wedding suit.

‘You’ve had a lot on your plate,’ I said. ‘How’s he doing? How’s Just?’

‘He’s coming out of hospital soon,’ she said. ‘He’s coming home.’

‘I’ll drive you,’ I said, wanting to do something for the pair of them, wanting to make it right, and knowing that I never could. I felt my face burning because it seemed like a pathetically inadequate thing to offer, to drive Whitestone and her son from one end of the Holloway Road to the other.

But she shot me a grateful smile.

‘That would be a big help, Max,’ she said. Then she nodded at the door, and the perimeter beyond, suddenly all business. ‘Let them in,’ DCI Whitestone said.

We went deeper into the city.