But Grandad insists on tucking the package into the pocket of my jeans alongside the map. “It’s fine: totally consumable. After Win’s eaten it, you can burn the paper towel. I promise Crowky won’t be using my rocky road to get out of Roar!” Grandad chuckles at his joke, but I only manage a weak smile. “Now are you two going to Roar or what?”

“Yes!” cries Rose, and I follow her as she bounds up the stairs two at a time. Grandad follows. The closer we get to the attic, the more my stomach squirms, and when I see the cot, I actually feel dizzy. Am I feeling excitement or fear? It’s really hard to tell.

“Are you sure it will work?” I ask Rose, eyeing the mattress. “It took me loads of tries to get to Roar last time.”

“Course it will work,” she says, confidently. “Just think of Roar and you’ll find your way there.”

“What about underpants?” I blurt out. Suddenly, I want to delay the moment I put my head inside the bed.

“What?” says Rose.

“Well, we can’t wear one pair of underpants for the whole week, can we? It’s disgusting!”

Rose shakes her head. “Arthur, you do realize how bad it will look if Crowky escapes from Roar because you need clean underpants?”

Grandad chuckles and draws a banner in the air. “Arthur Trout’s Fresh Underpants Obsession Destroys Humanity! Don’t worry about your under-crackers, mate. You can wash them in the waterfall. Now who’s going first?”

“Me!” says Rose, and then she gives Grandad a big hug before kneeling in front of the bed. We watch as she pushes her head and arms into the mattress, then starts wriggling forward. For a moment she looks like she’s stuck, but after a bit more twisting she manages to pull her legs and feet up behind her. Now her body is completely hidden inside the folded mattress.

Grandad and I stand next to each other and stare at the Rose-shaped bulge. At first nothing happens. Then the bed shudders, there’s a squeak of rusty springs . . . and Rose is gone.

“Blimey,” says Grandad, circling the bed. “I’ve never actually seen it happen. You must have gotten the shock of your life when I disappeared!”

“Something like that,” I say.

He looks at me. “Don’t you think you should get going, Arthur? I want you two to stick together in there. I don’t want Rose going into Roar on her own.”

“No,” I say. “Right. Here I go.” Only I don’t go. I stand there, staring at the bed, my heart thudding.

“Come here,” says Grandad, pulling me to him.

I press my face into his slightly wheezy chest and smell coffee and his sweater. “I think I’m scared, Grandad.”