And in the memory, she feels Mumma move off the bed. She opens her eyes just a little and sees Mumma stand up and look out of the window. It must be morning, because Mumma’s face is lit up and she looks worried. Gaia is still so sleepy. She mumbles something to Mumma, but she doesn’t respond.

Next thing Gaia knows is her mumma is gone, and she knows from the look on her face and from the language without words that exists between them that her mumma has seen something outside, something very strange and concerning. Her mumma has gone out to check. Gaia’s still floating in that warm dreamspace of sleepiness and it’s much too early to get up because her clock hasn’t even made the buzz noise that Mumma told her it has to make before she’s allowed to come into her room. This is Mumma’s effort to make Gaia sleep in her own bed, even though Gaia much prefers Mumma’s bed, which feels as though it’s made of swan’s feathers and summer clouds. She hears footsteps on the landing and smiles – Mumma’s coming back. But the footsteps don’t sound like Mumma’s, and she raises her head just enough to see someone else go past the bedroom door. It’s Derry. Gaia hears the sound of the kitchen door swing shut, then the sound of Derry’s feet jogging through the garden.

When Gaia wakes again, it’s already morning. Proper morning, with the sun already up and the clock buzzing away. She taps the buzzer down and jumps out of bed. Mumma’s not in her own bed. She’s not in the playroom. Gaia heads to the window and pulls up a chair to look out the window. There’s a strange mist rolling over the fjord. It looks like ghosts. And somehow, deep in her mind, she knows something is very wrong.

She’s upset and frantic and tearful and has no idea why, but she feels like she’s trapped in a huge spider web and has to break free of a thousand silken threads that bind her. She goes back to her bedroom for Louis and climbs back into bed. She hugs him tight, then sobs and sobs because it’s been ages since she saw Mumma, and she wants her back right now.

‘Look,’ Louis says.

She looks down at the floor.

‘What do you think it is?’ she asks Louis.

She gets out of bed and looks at the markings. Two muddy curves, like two Cs facing each other, one a normal C and the other a back to front C.