Matt felt his stomach flip inside – though the moon still gave them a faint twilight, the ocean at night meant that the depths of their vision ended in shadows that moved behind curtains of darkness.

Each of them swam like seals as they rocketed out of the fissure in the sunken island, along the bottom, and headed for the safety of their boat. They moved fast, huge diving fins paddling strongly, but where they were like seals, the things coming out of the darkness were living torpedoes.

Matt was thankful for the glow of the moon, as he could at least see the sharks’ circling, some small and under six feet, moving erratically and agitated, working themselves into the mindless mass that would become a feeding frenzy. But further out, at the very extent of his vision, he could make out larger shapes, huge, as thick around as a draft horse, and longer than their boat – the ocean’s apex predators, the great white.

A shark peeled off and lunged in toward them, seeming to pick out Abrams as its target. Hartogg slashed at it, his blade pummeling the tough hide, but not opening or even denting its rough skin. It turned away, but another immediately took its place.

Again and again, they came at Abrams, and Matt knew why – it was the Book. These primordial creatures, 450 million years in the making, were either seeking to attack the Book itself, or were perhaps trying to defend it from the mammalian apes that sought to steal it.

There came a thud, a grunt and an explosion of bubbles. Matt saw Andy tumbling in the water as a seven-foot bull shark flicked away.

Adira was first to the anchor rope, and looked up. The ascent was where they would be most vulnerable: especially in the moment they would need to look away and lift themselves from the water. The image of kicking, dangling legs among all the man-eaters made Matt feel sick from fear.

Adira pointed up, and then held up five fingers. She swam away a dozen feet, and then used her knife to open a slit in one of her palms. Black blood immediately clouded the water around her.

Matt knew what she was doing – drawing the beasts to her. With blood in the water they could expect the furious eating machines to be driven into a frenzy of attack.

Adira turned and furiously pointed to the surface. Abrams pulled on Tania’s arm, and the two of them started guiding the groggy Andy up the anchor rope to Mahmood’s boat. Hartogg ignored Adira, and swam towards her.

The Mossad agent looked to Matt as she hovered in the water. She seemed to offer him a slight bow. Hartogg saluted, and Matt bet that behind his breathing equipment the big man was grinning. These people have no fear in them, he thought. He began his own swim upward, but couldn’t leave the soldiers to their fates. He paused, hanging by the rope, looking down.