“It’s none of your business, Garcia. Let’s go.”

“You paid for two passengers.” Garcia held up two withered fingers, every bone and sinew showing through. “Two passengers… that was what we agreed.”

“You’re being paid well enough. There’s no point arguing. The boy’s coming and that’s the end of it!”

After that, Garcia fell into sullen silence. Not that there would have been any point talking anyway. The noise of the engine was too great.

Alex watched as the coastline of Cayo Esqueleto slipped past. He had to admit that Blunt had been right-the island was strangely beautiful with its extraordinary, deep colours; the palm trees packed together, separated from the sea by a brilliant ribbon of white sand. The sun was hovering, a perfect circle, over the horizon. A brown pelican, clumsy and comical on the ground, shot out of a pine tree and soared gracefully over their heads. Alex felt strangely at peace. Even the noise of the engine seemed to have drifted away.

After about half an hour, the land began to rise up and he realized they had reached the north point of the island. The vegetation fell back and suddenly he was looking at a sheer rock wall that dropped all the way, without interruption, to the sea. This must be the isthmus that he had been told about, with the road leading to the Casa de Oro somewhere at the top. There was no sign of the house itself but, craning his neck, he could just make out the top of a tower, white and elegant, with a pointed red slate roof. A watch-tower. There was a single figure framed in an archway, barely more than a speck. Somehow Alex knew that it was an armed guard.

Garcia turned off the engine and moved to the back of the boat. For such an old man, he seemed very agile. He picked up an anchor and threw it over the side, then hoisted a flag-this one more identifiable than the others. It showed a diagonal white stripe on a red background. Alex recognized the international scuba-diving sign.

Troy came over to him. “We’ll go down here and swim in to the coast,” she said.

Alex looked up at the figure in the tower. There was a glint of sunlight reflecting off something. A pair of binoculars? “I think we’re being watched,” he said.

Troy nodded. “Yes. But it doesn’t matter. Dive boats aren’t allowed to come here but they sometimes do. They’re used to it. The shore is strictly off-limits but there’s a wreck somewhere… people swim to that. We’ll be fine, provided we don’t draw attention to ourselves. Just don’t do anything stupid, Alex.”

Even now she couldn’t resist lecturing him. Alex wondered what he would have to do to impress these people. He said nothing.

Turner had taken off his shirt, showing a hairless, muscular chest. Alex watched as he stripped down to his trunks, then pulled on a wetsuit which he had taken from a small cabin below. Quickly the two CIA agents got ready, attaching air cylinders to their buoyancy jackets-BCDs-then adding weight belts, masks and snorkels. Garcia was smoking, sitting to one side and watching all this with quiet amusement, as if it really had nothing to do with him.

At last they were ready. Turner had brought a waterproof bag with him and he unzipped it. Alex noticed the Game Boy sealed in a plastic bag inside. There were also maps, torches, knives and a harpoon gun.

“Leave it all, Turner,” Troy said.

“The Game Boy…?”

“We’ll come back for it.” Troy turned to Alex. “Right, Alex,” she said. “Listen up! We’re going to make an exploratory dive to begin with. We’ll be gone about twenty minutes. No longer. We need to find the cave entrance and check there are no security devices in operation.” She glanced at her watch. It was only half past six. “The sun won’t set for another hour,” she continued. “We don’t want to spend that long sitting in the cave, so we’ll come back to the boat for the rest of our equipment, change tanks and make a second journey back. You don’t have to worry about anything. As far as the people in the villa are concerned, we’re just tourists doing a sunset dive.”

“I’m a qualified diver,” Alex said.

“The hell with that!” Turner cut in.

Troy agreed. “You talked your way onto the boat,” she said. “Fine. Personally, I wish you’d stayed in the hotel. But maybe you were right about that, it might have raised suspicions.”

“You’re not coming with us,” Turner said. He looked at Alex coldly. “We don’t want any more people killed. You stay here with Garcia and leave the rest to us.”

The two agents made their all-important buddy checks, each one looking over the other’s equipment. No pipes twisted. Air in the tanks. Weights and releases. Finally, they went over to the side of the boat and sat with their backs facing the sea. They both put on their fins. Turner gave Troy the all-clear sign: second finger and thumb forming an O, with the other fingers raised. They lowered their masks and rolled over backwards, disappearing immediately into the depths of the sea.

That was the last time Alex saw them alive.

He sat with Garcia on the gently rocking boat. The sun was almost touching the horizon and a few clouds, deep red, had intruded into the sky. The air was warm and pleasant. Garcia sucked on his cigarette and the tip glowed.

“You American?” he asked suddenly, speaking in English.

“No. I’m English.”

“Why you here?” Garcia smiled as if amused to find himself alone at sea with an English boy.

“I don’t know.” Alex shrugged. “How about you?”

“Money.” The one word answer was enough.

Garcia came over and sat down next to Alex, examining him with two dark eyes that were suddenly very serious. “They don’t like you,” he said.

“I don’t think so,” Alex agreed.

“You know why?”

Alex said nothing.

“They are grown-ups. They think they are good at what they do. And then they find a child who is better. And not only that. He is an English child. Not an Americano!” Garcia chuckled and Alex wondered how much he had been told. “It makes them feel uncomfortable. It’s the same all over the world.”

“I didn’t ask to be here,” Alex said.

“But still you came. They would have been happier without you.”

The boat creaked. A light breeze had sprung up, rippling the flags. The sun was sinking faster now and the whole sky was turning to blood. Alex looked at his watch. Ten to seven. The twenty minutes had passed quickly. He scanned the surface of the ocean but there was no sign of Turner or Troy.

Another five minutes passed. Alex was beginning to feel uneasy. He didn’t know the two agents well, but guessed they were people who did everything by the book. They had their procedures, and if they said twenty minutes, they meant twenty minutes. They had been underwater now for twenty-five. Of course, they had enough oxygen for an hour. But even so, Alex wondered why they were taking so long.

A quarter of an hour later, they still hadn’t come back. Alex couldn’t disguise his fears. He was pacing the deck, looking left and right, searching for the tell-tale bubbles that would show them coming up, hoping to see their arms and heads breaking the surface of the water. Garcia hadn’t moved. Alex wondered if the old man was even awake. A full forty minutes had passed since Turner and Troy had submerged.

“Something’s wrong,” Alex said. Garcia didn’t answer. “What are we going to do?” Still Garcia refused to speak and Alex became angry. “Didn’t they have a back-up plan? What did they tell you to do?”

“They tell me to wait for them.” Garcia opened his eyes. “I wait an hour. I wait two hours. I wait all night…”

“But in another ten or fifteen minutes they’re going to run out of air.”

“Maybe they enter the Devil’s Chimney. Maybe they climb up!”

“No. That wasn’t their plan. And anyway, they’ve left all their equipment behind.” Suddenly Alex had made up his mind. “Have you got any more scuba gear? Another BCD?”