I’m about to say something when a sound cuts through the night air. It’s a screeching, roaring wail, and when it dies down, I find I’m clinging on to Violet and she’s clinging on to me.

“OK, and what’s that?” she exclaims.

“Close,” I reply. “That’s what that is. Too close.”

As our eyes adjust to the moonlight, we see that the strange, pulsating red star-that-isn’t-a-star isn’t in the sky at all, but in a window. The window of an old tower, above the battlements.

“That’s the museum,” I say.

“Dr Thalassi’s museum?”

Just then the terrible, shrieking wail comes again, echoing in the narrow street, and the red light winks out altogether. For a moment, as we watch, a dark and spiny shape seems to scuttle up the wall of the tower – but when I blink to make sure I’m not seeing things, it disappears.

“We should go,” I say, trying not to squeak.

“We certainly should,” says Vi. “Before we miss something important.” And she hurries off towards the museum.

“Wait!” I grab her coat. “I didn’t mean that way. I meant back to the hotel.”

“But the adventure is that way.” Vi pulls herself free. “Not back in the hotel.”

“But back in the hotel there aren’t any strange lights or terrible nightmare sounds!” I squawk, flapping my arms.

“Curiosity may have killed the cat, but that doesn’t mean cats shouldn’t be curious.”

“Ha!” I cry. “That’s easy for you to say.”

“Except…” Vi replies, blinking, “except I didn’t say it. He did.”

I look to where she’s nodding. Erwin is sitting on a nearby window ledge, giving us both a significant look.

“Seriously?” I say to him.

But the cat just purrs and licks his paw like any other cat in the world. And by the time I turn back to Violet she’s already running off into the dark, towards the museum.

So there’s nothing left for me to do but run after her.

I catch her up as she’s heading down another flight of steps and out into a dimly lit street. From here I can see Mrs Fossil’s Flotsamporium. There is a light on somewhere inside, and I wonder how Mrs F is doing, but I can’t stop to knock now – Violet is off again. It’s only when we come out onto the battlements, at the fortified western end of town, that Violet finally comes to a halt. She crouches in a shadow and nods across the expanse of cobbles to a crenellated medieval building that hulks on the other side.

“Is this it?” she whispers.

“Yes, the museum is in the old castle,” I whisper back. “Well, the doctor’s surgery takes up some of the ground floor part, but all that up there is the museum, including the tower.”