They had come out here at first light, and ever since had been taking turns to dive, exploring the ocean floor, searching for the cave. Forest was diving right now – there were plenty of rocky crags and reefs to work through.

A yellow float bobbed on the surface, tied to Forest below. The boy really was remarkably good at diving, and Ahab knew that for all his cockiness, he had the right instincts to take care of himself down there. Still, Ahab kept an eye on the float as it moved around while he took a much-needed break.

He heard the dinghy powering out towards him before he saw it. For a wild moment he thought it was the Black Wind, but then he saw Ned’s boat. Except it wasn’t Ned steering it, it was Mackenzie Dempsey.

He pulled the little dinghy up alongside the Ambergris, on the opposite side to Forest’s buoy, tethering it to the larger vessel and lowering a curtain of foam down over the side so the hulls wouldn’t scrape against each other.

Mackenzie climbed up the ladder, his movements setting it to tink with each step. When at last he stood before Ahab, he wouldn’t make eye contact. He’d had a haircut, a shave, and his clothes were not exactly seafaring gear. They were the clothes of a man with money. Mack wore them well, but something in his face told Ahab they weighed heavy on his shoulders.

There was a splash off the other side of the boat, where Forest had surfaced, having heard the boat approaching. He made the okay? sign.

Okay, Ahab signed back.

‘Ned told me where to find you,’ said Mackenzie. ‘Let me borrow his boat.’

‘I can see that, son,’ said Ahab.

Mackenzie looked up. Ahab saw now that his eyes were bloodshot and his chin wobbled. That face told him everything he needed to know.

‘Ah, mate,’ said Ahab. ‘Did you bite off more than you can chew?’

‘I c-can’t do this,’ said Mackenzie. ‘I can’t.’

‘Why not?’ said Ahab, gesturing for him to take a seat.

Mackenzie did so, crumpling in on himself.

‘I left that world behind once already – I can’t go back! I’ve got court coming up soon!’

‘Then don’t,’ said Ahab. ‘No one is forcing you to.’

‘But Shelby can’t do it without me,’ said Mackenzie. ‘Blackbeard is —’

‘Blackbeard this, Blackbeard that,’ interrupted Ahab. ‘The man’s reputation is bigger than he is. I promise you he’s flesh and blood, just like you and me.’

‘You don’t get it,’ said Mackenzie. ‘He’s more dangerous than that.’

‘You have a choice, you know?’

‘I can’t. I’m not strong enough. It’s too tempting.’

‘What is?’ said Ahab. He found it hard to imagine, after all he’d been through, that Mackerel could still be seduced by it all. ‘What’s tempting about it?’