She nodded. ‘And the ARV couldn’t follow. Too dangerous. They’re trained to shoot straight, not drive like Lewis Hamilton. They phoned ahead and by the time we found the white van – twenty minutes later – it was on fire.’

The Chief Super’s mouth twisted with annoyance. ‘They took you to the kill site, Max. Any thoughts on where it could be?’

I thought of the square room with the decaying tiles, turned green by a century of neglect, and the corridor they had led me down, where the walls and the ceiling were always closing in on me. Had I imagined that? In the bright light of the morning, I wasn’t sure how much of the night had been real and how much the fevered imaginings of pure terror. There was a smell – wasn’t there? It was sweet and rotten, like dead flowers, or sugar in a sewer. A rank sweetness that I knew from somewhere – or was that just in my head?

‘We drove into the city,’ I said. ‘Somewhere very central. Underground. An abandoned building that was important a century or so ago. But I don’t even know where you found me. Nobody’s told me. I thought I saw a sign on the wall that said Bloomsbury . . . No, I mean, I definitely saw a sign on the wall that said Bloomsbury – but I never heard of a tube station with that name.’

‘The tube station you found was closed in 1933,’ Whitestone said. ‘It was originally called British Museum. They were going to call it Bloomsbury but they changed the name before it ever opened. And in 1935 – a couple of years after it was closed – they shot a scene in a film called Bulldog Jack down there – a swordfight – and the producers put up signs saying Bloomsbury.’

‘With Fay Wray,’ Swire said. ‘The King Kong girl.’

‘I was looking at . . . a film set?’

‘The tube station was real, Max,’ Whitestone said. ‘Only the sign was fake.’

‘But if we know that I was in this tube station,’ I said, ‘then our search teams must be able to find the kill site.’

Whitestone shook her head.

‘They’re looking,’ she said. ‘But it’s not that simple. London has hundreds of miles of disused tracks and literally dozens of abandoned underground stations. We know the one you came out of, but you don’t know how far you walked and you don’t know what direction you came from.’

‘What about the Dog Support Unit? The sniffer dogs must be able to follow my trail from Bloomsbury back to the kill site?’

‘Do you know the best way to distract a sniffer dog, Max?’ Whitestone asked me.

‘Introduce another animal, prey or food,’ I said. ‘Villains call it hiding the ball. You introduce a scent that’s strong enough to distract the sniffer dogs from what they’re meant to be hunting. Is that what they did?’