She grabs the spindly chair from under the tiny desk, and pulls it over to the wardrobe. In a moment, she’s teetering on top of it in her mother’s boots, rummaging around in a cloud of dust of her own making.

“Doesn’t anyone ever clean in this hotel?”

“There are hundreds of rooms, you know,” I say. “And anyway, why would anyone clean up there?”

“Because of these,” says Violet, and she jumps down from the chair. She is holding a bunch of papers and pieces of card and things, which she spreads out on the bed. There are several till receipts, tags that have been cut off holiday clothes, a foreign coin, two Pokémon cards, and…

“Aha!” cries Violet, snatching something up in both hands. It’s the size of a postcard, and has a line of numbers and letters printed on it. Violet cries, “Yes!” and holds it up to me. On the back of the card is a drawing of a crooked little monkey (or is it a chimp?) in a top hat – a monkey with a fish’s tail.

In a moment, Violet has pulled out the dog-eared card that she keeps on a ribbon around her neck. She holds them both up. They match.

“The numbers and letters are different,” I say. “And any one of the guests who’ve stayed here could have left that card.”

“What?” Violet looks unimpressed. “Are you saying it’s a coincidence? That two such freaky postcards just happen to be in the same room at the same time, and it’s not connected? How can you say that? Unless –” she turns on me – “unless you know something about these cards.”

I straighten my cap again and meet her gaze. Almost.

“Herbie! You do know something, don’t you! You recognize these weird monkey cards.”

“OK, OK, maybe I do,” I say, a bit mumbly.

“When were you going to tell me?” Violet demands.

And I wonder again why I didn’t say something when I first saw the card around Violet’s neck. Then I remember it was because I didn’t want to encourage this whole detective nonsense, that’s why. And yet here I am, the next day, stealing keys and searching for clues and helping a secret girl climb up the fire escape. It’s probably about time I just gave in and accepted that I am on a case now, whether I like it or not.

“It’s a prescription card from the Eerie Book Dispensary,” I say, throwing my hands up in surrender. “Most people round here have them. It’s really nothing unusual.”

“Nothing unusual?” Violet is starting to get cross, I can tell. “If it’s nothing unusual, why have I no idea what on earth a, a … what did you call it?”

“A prescription card,” I say. “From the Eerie Book Dispensary.”

“Why do I have no idea what that even is?”