Porter looked up at the bolted door.

OK, he thought, feeling the resolve stiffen inside him. Let’s see if we can’t make some trouble for these bastards.

He collected the tiny candle, holding it up close to the door. There was enough of a crack that he could see out into the corridor. From here, it looked empty, but that didn’t mean there wasn’t a guard just a few metres away. The bolt was made from metal, and slotted into position in a socket about four feet off the ground. Porter positioned himself close to the door, and held up the candle so that he had as much light to work with as possible. He slotted the knife into the gap in the door, and slowly worked it against the bolt: he dug the tip into the metal, twisted it to get as much grip as possible, then used all the strength in his wrist to flick it backwards a couple of millimetres. It didn’t move much, but it did shift a fraction, and to Porter that was all that mattered. He would get there eventually.

It took ten minutes, maybe fifteen, but eventually the lock was freed. He reckoned it was three fifteen in the morning now, although he couldn’t be certain. The door swung open: Porter had to grab hold of it to stop the thing from crashing back and raising the alarm. He blew out the candle, and held his breath tight in his chest. Very slowly, and with the knife gripped in his right hand, he squeezed the door ajar. He glanced into the corridor. The light was murky – there were some lamps in the meeting point but nothing in the corridor – and although he had got used to the semi-darkness it still took a second for Porter to adjust his eyes. So far as he could see the corridor was empty. He inched out, keeping one foot inside the door, so that he could snap back inside if necessary.

Porter already had a plan mapped out. He’d have liked to go straight to Katie, but that route was too well guarded. There was no way he could get through equipped just with an eating knife. Instead, he’d slip through to Hassad’s room. It was a distance of about twenty metres through the tunnels, and he calculated there would only be one guard along the way. The odds of success weren’t great, he thought. But at least they weren’t suicidal.