It was cold, claustrophobic, horrific. There was none of the magic of diving. In its place was only terror. Sometimes, when he brushed the side of the cave, he felt something like a static shock rushing through him, pressing on his ears, making him nauseous.

It was useless – he might as well give up. Out there in the currents of the open sea, what would they do? It would be impossible to find their way back to the gravel beach with the path to the cliff. Ahab was blind. Ahab was dead weight. It wasn’t fair on Mackenzie or the boy for him to keep holding on. He’d only end up killing them.

He heard the singing-drone intensify – the sirens’ song – and then he felt the three of them being sucked back towards the cave, the whirlpool growing stronger. Eyes tightly shut, breathing with Mackenzie’s safety regulator, Ahab gripped the kelp and wedged himself in place, trying to stop them all getting sucked back into the cave.

When it finally passed, he felt Mack pulling forward. He added his own kicks, fuelled by the adrenaline of survival.

A sudden swirl of current – Ahab’s head pounded into a rock. Even as stars sparkled in his vision, he fought it off, fighting for consciousness.

And then, just like that, he sensed a shift in the current. They were out of the tunnel, out into the wide-open water. Clinging to Mackenzie, he felt them being thrown around by the currents. For a long while he kicked in the dark, limbs growing sluggish.

Then there were heavy rocks against his legs, and waves pounding on top of him. He felt someone shaking him, saying something he could barely make out. He opened his eyes, blinking against the light. The waves were pulling at him. He was tired, just . . . so tired. It’d be beautiful to just let the waves take him out to sea. He was done, so done . . .

Mackenzie grabbed him and he felt himself being dragged along gravel, then pushed up against cold rock. Mackenzie was shouting in his face, ripping the BC off him, but he had to concentrate to understand what he was saying.

‘C’mon, Ahab! C’mon! We’re on land, we’re safe, we just have to get up this switchback!’

But Ahab was too exhausted to ever move again.

CHAPTER 58

FOREST

‘He’s not too good,’ shouted Forest over the thundering sound of the waves crashing into the cliffs. He was holding Ahab against his chest. An almighty storm raged all around them, the rain driving down in sheets, flashes of lightning off on the horizon.

They were pushed right to the back of the gravel beach, each surge threatening to pull them in. Forest’s heart was pounding from the effort of swimming out of that cave, his throat was raw from exertion, and he was freezing.