I

Knox kept his eyes fixed on the knife as it tumbled in slow motion through the water towards him, all too aware it was his one hope of escaping death. He reached up for it but it caught on an eddy and bumped the heel of his palm then bounced down his forearm and shoulder before vanishing behind his back. He spun around but it was already level with his waist by the time he saw it again. He grabbed for it but it was elusive as soap in a bath and then he reached the end of his fishing-line tether and was jerked back. He watched in horror as the knife fell past his knee and calf, but he reached out a foot beneath it, trying to keep his movements slow so as to avoid creating eddies.

The knife hit his flipper point first, then fell on to its side, half the hilt hanging precariously over the edge. He reached for it but again his tether held him back. He was out of air now, running on fumes, so he lifted up his foot. The knife tumbled over the side but he grabbed it and caught it and instantly brought it up to his throat, laying the blade sideways so that he could get its tip beneath the fishing line, then twisting it and pressing out and suddenly it snapped and he was free, able to breathe once more, sucking great draughts of air back into his starving lungs.

It was a good minute before he was sufficiently recovered even to think of next steps. He carefully turned the knife around in his hands then used it to free his wrists of the flexi-cuffs. He looked up again. Boris was still thrashing around above him. Despite everything, he felt wretched for the man. The bends were as painful as anything on earth, like having spikes hammered through all your joints. Yet there was nothing he could do for him right now; he had to give his own body time to adjust to the lesser pressure or he’d suffer a similar fate himself.

When finally he surfaced, Boris was whimpering and weeping in the water, the pain too great to manage. Mild cases of the bends could be treated with pure oxygen, which was why Knox kept a small tank of it in his dive-bag, but Boris was beyond that. His one hope was the decompression chamber on board the Maritsa. Knox grabbed his collar and tried to drag him to the Yvette, but he was thrashing so wildly that Knox finally let go of him and swam over to the boat himself then motored it back across, trying unsuccessfully to raise the Maritsa as he came, hoping to get them to meet him halfway.

Boris’s cries had diminished by the time Knox pulled alongside, exhaustion rather than slackening of the pain. Knox snagged him with a boat-hook, dragged him around to the stern, hauled him aboard. He curled up on the deck like a foetus, his teeth stained red with blood, more blood and mucus leaking from his nostrils. Knox took his oxygen from his bag, attached its breathing mask and clamped it over Boris’s mouth. ‘I need to get you to my dive-ship,’ he told him. ‘You’re going to have to hold the mask, okay?’

Boris reached up and took Knox’s wrist, dragged it down so that he could speak. ‘You lied to me,’ he said.

‘Yes,’ said Knox.

‘I knew it,’ he said, tears of pain and regret streaming from his eyes. ‘I knew it and I still couldn’t let it go.’

‘Keep breathing,’ Knox told him.

‘What for?’ asked Boris. Pain wracked him; he arched and clenched Knox’s hand, then he fell limp with exhaustion. Blood began dribbling from beneath an eyelid, and from his left ear too, some terrible trauma taking place inside. His head lolled back and he looked up with what seemed like puzzlement at the afternoon sky. ‘I used to be a soldier,’ he said. Then he let go of Knox and his hand fell lifelessly against the deck.