And I give Erwin a hard stare, which he ignores as he purrs down to sleep.

“Anyway, now would be a good time to read your book, Violet,” I say as I head for the stairs. “And when I get back, maybe you’ll have some answers.”

Back up in my cubbyhole, I look both ways to make sure there’s no sign of Mr Mollusc in Reception. When I see that there isn’t, I stroll over to Amber Griss again. And again she watches my approach over her spectacles.

“Herbie,” she says, “if you’re going to tell me you’ve seen the croissant thief again…”

“No,” I say. “Not a sign. But I’ll keep my eyes open, I promise.”

“What have you done to get Mr Mollusc so worked up today?” says Amber. “He’s fuming.”

“I’m just returning these.” I put the keys to Room 407 on the counter. “They were lost, and I – er – I found them. It’s my job, after all. I don’t know what old Mollusc Breath is on about.”

“Now, now!” says Amber, suppressing a laugh as she takes the keys. Then she adds, “I wonder how these got lost.”

I give her one of my most innocent faces. “Who knows? Anyway, as part of my official duties as Lost-and-Founder, I need to look at the booking records,” I say, adjusting my cap and trying to look important. “I need to trace some guests.”

“I see.” Amber raises one eyebrow. “Do you know which room they stayed in?”

“Room 407, as it happens,” I reply, checking my fingernails.

“Really?” The eyebrow creeps even higher. “What a coincidence.”

Amber takes a large volume down from a shelf behind her, and opens it on the counter.

“They stayed here twelve years ago,” I say. “Maybe it would be better if I had a look?”

Amber stops flicking pages and gives me another over-the-spectacles glance. Then she turns the book round and pushes it over. It only takes a moment to find the entry for Violet’s missing parents, marked with the single word: Parma.

Vi’s dad’s name was Peter Parma. But Violet seems to know nothing at all about her mum, not even her name.

“Is there some way to find out more?” I ask Amber.

“People don’t need to give their shoe size to book a room here, Herbie,” she replies.

“But what about this phone number?” I say, tapping a column on the opposite page.

“We always take a phone number, for every booking. This looks like a London number. Why…?”

“Amber, it’s really vitally important that I use the hotel telephone.”

Amber Griss puts her hands on her hips. “Can you look me in the eye, Herbie Lemon, and swear that you’re not doing anything else to annoy Mr Mollusc?”