Two men carrying guns had approached the newly parked SUV. When Langdon and his driver stepped down from it, one of the men backed away, an eye on the street, while the other holstered his pistol and stood before my uncle. Langdon’s driver handed something over to the guard with the holstered gun. It was a cooler box. Langdon and the guard talked for a moment, Langdon with his hands on his hips, the guard with his arms respectfully at his sides. I couldn’t hear anything over the hum of the invisible city, not until Langdon threw his head back and laughed. Something in that gesture caught in my throat.

‘Are you thinking what I am?’ I whispered.

‘I don’t know,’ Amelia said, baffled. ‘What are you thinking?’

‘Armed guards. A warehouse in a wasteland. Langdon delivering whatever he’s delivering. A cool box. So, food, possibly?’

‘Those aren’t thoughts – they’re observations and guesses.’

‘Adding up to?’

‘The obvious possibility that your parents are in there.’

I turned to her.

‘The important word is possibility,’ she said patiently.

‘I disagree. It’s obvious.’

‘Another of your hunches is what it is.’

She was right, but this hunch was all I had.

Langdon raised a forefinger and wagged it at the guard, then spun on his heel. The wedge of light from the security lamp caught the side of his face. There was an odd shadow across his cheek. A bruise, I realised, as he stepped beyond the light and back to his car. I pulled Amelia behind the van, heard the growl of the SUV starting up again, watched its red tail lights bleed out down the street.

‘What now?’ Amelia asked.

‘I don’t know!’ I said. ‘Let’s watch for a while. See what those guys with the guns do.’

The answer to that was: not much. Occasionally one of the men would amble across the floodlit forecourt, but then he’d simply stroll back to his position on one side of the building’s roller-door entrance, which stayed firmly shut. There was no apparent pattern to these movements. It just looked like two bored guards keeping themselves from falling asleep by making a show of walking around.

‘I want to check the building, see if there’s a rear entrance, or a window I can reach,’ I whispered.

‘Yeah, but to do that you’ve got to cross beneath the light,’ Amelia said. ‘They’ll see you.’

She was right, but there was one solution: put out the light.

‘Reckon you can drive the bike?’ I whispered.

‘I’ve only been watching you and Marcel do it for about a hundred hours. How could I possibly have learned?’

‘OK, OK. When I say, drive it straight to the first junction down there. It’s about four hundred metres away if I remember rightly. Anyone follows you, keep going. If not, wait for me there. OK?’