There were no plants down in these caves, not even moss – the only life was cave spiders, their webs shimmering from their headtorches. Silent, his breath in his ears, the cold pressing down on him, Ahab followed the boy’s lead.

He didn’t mind caves, but night-time would not be his chosen time to go exploring in tidal caves, following a mysterious boy, on a quest to find what Ahab was quickly realising must be a tomb . . .

‘How much further?’ said Ahab.

‘Only a little way . . .’

Easy enough for the boy to say – he was small enough to move comfortably.

Stooped over, Ahab noticed footsteps and scuff marks in the dirt.

‘You’ve been here recently.’

‘The other night. Don’t worry, old man, we’re not lost.’ His voice had taken on an odd, dead tone.

They moved deeper into the cave network, and he saw the seaweed on the walls – they were in the tidal section of this tangle of tunnels.

‘And here it is . . .’ said Forest. ‘Stick your head in. Have a look.’

The crack in the wall was slight – you would have missed it if you didn’t know to look for it. Ahab hesitated only briefly, wondering about the wisdom of turning his back on the boy, then squatted in front of it and smelled the damp, salty brine beyond. Whispering air and echoes suggested a larger space beyond.

He stuck his shoulders through, but that was as far as he could get – he could feel the rock pressing on his back.

He’d been right: it was a tomb.

The cave was wide and long, and his headtorch cast jagged glistening shadows. On a floor of tightly clustered boulders there were two gluggy corpses, splayed out, thrown about by years of ebbing and flowing tides. The remains of one set of scuba gear were wedged in the rocks between them.

Alexandra and Forest.

He’d tried to prepare himself, but that sight still ruptured something deep inside him that he’d been trying to protect for years.

He tried to fight them but tears blurred his eyes. He blinked them away, moved his torch beam back and forth between the two bodies. It wasn’t hard to determine what had happened. Trapped, when the tide filled the chamber, they had drowned here. He couldn’t allow himself to look away from that. It was important to bear witness, to pay his respects and, in a way, make his apologies for his failures.

Then something caught his eye.

He backed out carefully, pulling himself together as best he could.

‘Get in there, boy,’ he said gruffly. ‘I need you to bring me Forest’s skull.’

‘Are you kidding? No way am I touching his body!’

‘It’s not like that,’ said Ahab. ‘It’s . . . I don’t think that’s Forest in there.’

‘. . . What?’ The boy looked horrified. ‘Who else would it be?’