The Lost Girls are proof of this. Since we set off they’ve been running up the stairs ahead of us, pausing every now and then to wait for us to catch up. Right now Flora and Hannah are climbing on the banister, which is basically a collection of loosely arranged twigs. “Is that safe?” I ask as they swing out over the huge drop.

“No,” says Stella, followed by, “Oi, you two, that’s delicate. Get off there before you break it!”

Win peers over the edge. “Arthur, you’ve got to see this. We’re so high up. It’s like a cliff!”

“Not looking,” I say, keeping close to the wall. I may have gotten over my fear of heights, but not my fear of you’ll-definitely-die-if-you-fall-down-there heights.

“See that room?” says Stella, pointing down a gloomy passageway. “That’s where the scarecrow army lived. They didn’t have beds, they had posts!” We carry on up the stairs and she nods toward a door with a large feather carved into the wood. “And that’s where Crowky made his giant crows. We’ve turned it into the girls’ dorm.”

Crowky made his crows to spy for him and deliver messages. They look uncannily like real crows, only they’re bigger and if we see them we know we’re in trouble.

“Can we show them our bunk beds?” begs Audrey.

“Later,” says Stella. “They need to see my room first.”

After three more exhausting turns of the staircase we make it to the top of the castle.

“My bedroom,” says Stella, pushing open two heavy doors. “Otherwise known as Crowky’s lair. I took all the straw out of his nest, but otherwise it’s pretty much as he left it.” We step inside. Even though the room is dimly lit we can tell that it’s huge and round. We must be at the top of the tallest tower.

“Girls, open the shutters,” says Stella.

“YES!” they yell, and they rush out of a door and onto a balcony.

“I don’t usually let them go out there,” explains Stella as the door slams shut behind them. “It’s really dangerous.”

The Lost Girls run around the outside of the tower, flinging open the wooden blinds as they go. Light floods into the room and what I see makes me freeze.

I’m surrounded by cardboard boxes. They’re piled up everywhere. Some are plain, some have goldfish painted on their sides. The words What’s in the box? and Rose and Arthur are written all over them. I walk between them feeling slightly sick. Rose, I notice, has gone quiet.

“We found these down in the dungeon,” says Stella. “I got the girls to bring them up here so I could clear out Crowky’s stuff.”

I wipe a layer of dust off one. “Crowky tried to make the Box,” I say.

Win laughs. “And he tried a lot of times!”