Porter had tried to talk to Hassad when the Unimog had pulled away from its hiding place, but he told him to be quiet. His men had to rest. He handed around some pitta breads, spread with some kind of chickpea mixture, and they all swigged on the same bottle of water. He was grateful for the food even though it didn’t taste of much. Then the other blokes in the back went to sleep. As the vehicle powered forward, Porter couldn’t get any rest. He was trying to think, to straighten out in his own mind what had just happened, and what he needed to do next. He had no idea who had captured him, or why they wanted him dead. If it wasn’t Hassad, then someone must have leaked where he was, and what mission he was on. And that could only be someone back at the Firm.

By the time the Unimog came to a halt, even Porter was fighting off sleep, struggling to keep himself alert. He judged that it must be nine or ten at night. Only twenty-three hours or so until the deadline set for Katie Dartmouth’s execution. And probably my own as well, he reflected.

To Porter, their destination looked like a disused mine. The Mercedes had turned off the track, and down a steep, rough slope that led inside a massive crater. There was a roadblock across the track leading into it, manned by three armed men, and even though they knew Hassad they still checked the vehicle before letting it pass. Taking their security seriously, Porter noted. This place is hard enough to get into. It will be even harder to get out again.

Around him, he could see some tall cranes, and a long conveyor belt led along the length of the crater towards an old, abandoned processing plant. A metal mine, thought Porter. Maybe copper or zinc. The crater must have measured two hundred yards, by a hundred: perhaps they started with an open-cast mine and then went underground, because there were doorways dotted around the crater that looked as if they led down into mineshafts. A perfect place to keep a hostage. Discreet, easy to defend, and virtually impossible to escape from. Even if I did manage to get Katie loose, how would I ever get her out of here?

‘Wait here,’ said Hassad, as they all climbed out of the Unimog.

Porter stood for a moment next to the vehicle. The wounded man was already being taken towards one of the mineshafts, but the other men stayed behind next to Porter, all of them cradling their AK-47s in their chests. Porter was sure he could smell some wild flowers in the night air, and there was a musty, metallic aroma that came from the piles of broken ore scattered around the crater. Copper, Porter reckoned. He’d had a mate who’d been a plumber once, and whenever you met the bloke for drink, he always had the same smell of burnt copper clinging to his skin after a day’s work.