“I see the wharf!” cried the bowman, his words immediately followed by a sudden thump under the hull, the crack of broken timber and a general falling about in the boat, one of the lanterns going over the side into immediate extinguishment.

“We’ve struck!” shouted a pirate. He stood as if to leap over the side, but paused and looked down.

Hereward looked too. They had definitely hit something hard and the boat should be sinking beneath them. But it was dry. He looked over the side and saw that the boat was at rest on stony ground. There was no water beneath them at all. Another second of examination, and a backward look confirmed that rather than the boat striking a reef, the ground below them had risen up. There was a wharf some ten yards away but its deck was well above them, and the harbour wall a barrier behind it, that they would now need to climb to come to the treasure houses.

“What’s that?” asked the gold-toothed pirate uncertainly.

Hereward looked and fired in the same moment, at a seven-foot-tall yellow starfish that was shuffling forward on two points. The bullet took it in the midsection, blasting out a hole the size of a man’s fist, but the starfish did not falter.

“Shoot it!” he shouted. There were starfish lurching upright all around and he knew there would be even more beyond the lantern-light. “Sea-Cat, ware shallows and enemy!”

The closer starfish fell a second later, its lower points shot to pulp. Pirates swore as they reloaded, all of them clustering closer to Hereward as if he might ward them from this sudden, sorcerous enemy.

Louder gunfire echoed in from the tunnel. Hereward saw flashes amid the steady light of the xebec’s lanterns. The Sea-Cat’s bow-chasers and swivel guns were being fired, so they too must be under attack. He also noted that the ship was moving no closer and in fact, might even be receding.