For the hundredth time, Alex cursed Alan Blunt, using language he hadn’t even realized he knew. It was almost five o’clock in the evening, although it could have been five o’clock in the morning; the sky had barely changed at all throughout the day. It was gray, cold, unforgiving. The rain was still falling, a thin drizzle that traveled horizontally in the wind, soaking through his supposedly waterproof clothing, mixing with his sweat and his dirt, chilling him to the bone.He unfolded his map and checked his position once again. He had to be close to the last RV of the day—the last rendezvous point—but he could see nothing. He was standing on a narrow track made up of loose gray pebbles that crunched under his combat boots when he walked. The track snaked around the side of a mountain with a sheer drop to the right. He was somewhere in the Brecon Beacons and there should have been a view, but it had been wiped out by the rain and the fading light. A few trees twisted out of the side of the hill with leaves as hard as thorns. Behind him, below him, ahead of him, it was all the same. Nowhere Land.

Alex hurt. The 22-pound bergen backpack that he had been forced to wear cut into his shoulders and had rubbed blisters into his back. His right knee, where he had fallen earlier in the day, was no longer bleeding but still stung. His shoulder was bruised and there was a gash along the side of his neck. His camouflage outfit—he had swapped his Gap combat trousers for the real thing—fitted him badly, cutting in between his legs and under his arms but hanging loose everywhere else. He was close to exhaustion, he knew, almost too tired to know how much pain he was in. But for the glucose and caffeine tablets in his survival pack, he would have ground to a halt hours ago. He knew that if he didn’t find the RV soon, he would be physically unable to continue. Then he would be thrown off the course. "Binned" as they called it. They would like that. Swallowing down the taste of defeat, Alex folded the map and forced himself on.

It was his ninth—or maybe his tenth—day of training. Time had begun to dissolve into itself, as shapeless as the rain. After his lunch with Alan Blunt and Mrs. Jones, he had been moved out of the manor house and into a crude wooden hut a few miles away. There were nine huts in total, each equipped with four metal beds and four metal lockers. A fifth had been squeezed into one of them to accommodate Alex. Two more huts, painted a different color, stood side by side. One of these was a kitchen and mess hall. The other contained toilets, sinks, and showers—with not a single hot faucet in sight.On his first day there, Alex had been introduced to his training officer, an incredibly fit black sergeant. He was the sort of man who thought he’d seen everything. Until he saw Alex. And he had examined the new arrival for a long minute before he had spoken.

"It’s not my job to ask questions," he had said. "But if it was, I’d want to know what they’re thinking of, sending me children. Do you have any idea where you are, boy? This isn’t a holiday camp. This isn’t Disneyland." He cut the word into its three syllables and spat them out. "I have you for twelve days and they expect me to give you the sort of training that should take fourteen weeks. That’s not just mad. That’s suicidal."

"I didn’t ask to be here," Alex said.

Suddenly the sergeant was furious. "You don’t speak to me unless I give you permission," he shouted. "And when you speak to me, you address me as ‘sir.’ Do you understand?"

"Yes, sir." Alex had...