She picked up the phone to Xander and asked him to send Mukwege a message telling him we’d set off for the warehouse ourselves and asking him to follow on.

We hailed a cab, rode it to the spot where Amelia had waited all night and walked from there. My pulse was jumping as we approached the building. It looked so different in the early evening light, more boring, less sinister. I’d planned to stroll past it once and count the guards. They’d not seen either of us the night before so there could be nothing wrong with simply walking by. I doubted they’d do more than glance our way. The van from behind which I’d thrown the rock was still parked across the street. This time we walked in plain view on the other side of it. My feet stopped moving as the full expanse of the warehouse forecourt, smashed floodlight and all, spread out before us. I couldn’t see any guards out front at all.

‘Weird,’ I said.

‘Where have they gone?’

‘No idea,’ I replied. Were they round the back, or inside? That wouldn’t make much sense. A nasty thought flashed past: had we spooked them last night, prompting them to up sticks with their prisoners and move on?

Before I knew it I was running across that forecourt, Amelia trailing behind me, making straight for the warehouse’s front door. What was the worst those guards could do to me if they were inside? Lock me up with my parents, if my suspicions were right. The big roller-shutter covering the door was down, secured with a padlock through two metal hoops, one in the bottom of the door, the other embedded in the concrete floor. I hammered on that metal shutter, yelling, ‘Hello! Hello! Is there anyone inside?’

Bang, bang, bang. Again and again. Until my hand hurt.

‘You should probably pause to listen for an answer,’ Amelia suggested.

I gave another bang, bang, bang and waited.

Nothing. Then, from far away, a distant thump, thump, thump.

We looked at one another.

Bang, bang, bang.

Thump, thump, thump.

‘Mum? Dad!’

Silence.

Then, from so far away, ‘Jack!’

In a frenzy I tore around the building looking for a way in. There were definitely no guards: the place was deserted. There were no windows either, and the only other door, at the rear, was also made of metal and locked shut. While I was circling the warehouse, searching high and low, Amelia considered the situation her way, and when I next jogged past she pointed at the security light that I’d smashed, at the top of its long metal pole, and said, ‘That?’

‘What about it?’

‘Let’s rip it down and use it smash the lock.’