“The something,” I say, with a slightly wobbly voice. “The something he had grafted on instead of a hand… I, er, I don’t suppose the book says anything about what that something might have been?”

“It does, as it happens,” says Dr Thalassi. “It was a boathook.”

THE MUSEUM OF EERIE

“WHEN WAS THIS BOOK WRITTEN?” says Vi, after a shocked pause.

“Malamander?” says Dr Thalassi. “Oh, well over a century ago. I’d have to look it up.”

Violet turns to me. “It must be a coincidence, surely.”

“A coincidence?” says the doctor. “What is a coincidence?”

“What happened to Captain K?” Violet ignores the question by asking one of her own. “In the end, I mean?”

“No one knows for sure,” says the doctor. “Some say that even now he can sometimes be seen, wandering at night near the wreck, searching for the monster and his revenge. But that can’t be true; he must be long dead.”

“Are there any pictures of Captain K?” I ask, almost without squeaking. “Any old photos?”

“This is a museum,” says Dr Thalassi. “Of course there are old photos.”

We’re in the main exhibition space of the Eerie Museum, in the softly fizzing glow of the paraffin lantern. Above us the skeleton of a whale hangs suspended, and in the cabinets all around, stuffed and desiccated sea creatures peer out at us through glass eyes.

“Over here,” says the doctor, leading us to the far wall. “This display concerns the wrecking of the Leviathan.”

And there, amongst the nautical charts and brass instruments of navigation, we see what by now we are both dreading: a faded sepia photo of a man in a captain’s uniform, standing on the deck of an immense iron warship. This man is less grotesque, and with a neater, trimmer beard, but there’s no mistaking him.

“Boathook Man,” Vi whispers.

“He doesn’t have a boathook for a hand in this picture,” I say.

“He wouldn’t.” The doctor holds the lamp even closer so we can read the caption. “This was taken five years before all that happened. He was sixty years old at the time.”

“But that would make him …” I say, working it out roughly in my head, “getting on for two hundred years old! He can’t be.”

Violet looks as shocked as I feel. Dr Thalassi watches us with an inscrutable expression.

“It almost sounds,” he says, after a moment, “as if you think you’ve met Captain K. Even though that would be completely impossible.”

“Yeah,” I say. “Completely impossible.”

“Why is it so cold in here?” Vi pulls her coat tightly around herself.

“A window was broken, remember?” says the doctor. “I had better cover it up for the rest of the night, or I could have more intruders. You two can help me. Then I’ll walk you home.”