Inching my head past the rock, I see the group of Stone Age people, led by the biggest one with the square moustache. Two dogs sniff the ground. Craning a little further, I can see Seb, lashed to a large stake driven into the earth, with his hands tied behind his back. Next to him, similarly tethered, are three more people: our friends Kobi, Erin and Farook. Only, like the custard river becoming water, they have totally lost their cartoonish quality. They are no longer drawings come to life, but real people.

I was last here, what? Two nights ago? It feels a lot, lot longer.

Poor Seb is terrified and wriggling, trying to loosen the rough ropes that are binding his wrists, and drawing blood with the effort. He’s in the middle of a flat, dusty area, about the size of a tennis court, that has been cleared of bushes, with larger rocks and big logs positioned round it.

More seconds are ticking by and I weigh up the options.

We could run at them, armed with nothing? In a fight between two eleven-year-olds and a short, round old lady, and a group of Stone Age adults armed with long wooden spears, I know who is going to win. My dream-controlling abilities are close to zero now. If I am captured, the same might happen to me as to Seb and I will be trapped forever in a dream of my own making. And what if I am killed? Will I die in real life, or will I just wake up?

Either way, I will not have Seb.

I feel a dig in my side from Susan. She points at some trees on the other side of the flat ground where something big is moving among the trees. I strain to see, but just get flashes of white and brown, and … hair?

Susan whispers to me: ‘Mammoth.’

As she says this, a sounds erupts from the trees: a loud, trumpeting growl as though Dennis, Kenneth’s old dog, has been crossed with an elephant.

‘That’s our distraction,’ she whispers. ‘Well – that and, erm … that.’ She jerks her thumb behind her, and I think I manage to stifle my shriek of horror.

Shielded from the view of the gang tormenting Seb, Susan’s grandmother has stripped completely naked and is smearing her body with handfuls of mud and dust. She’s rubbing it all over her prominent belly and her … and her … well, everywhere, really. Including her hair. In fact, especially her hair, which is now standing on end, aided by large amounts of dirt.

I concentrate on looking at Mola’s head because I don’t really want to look anywhere else.

I manage to speak, but it comes out as a croak. ‘Is … is this my dream? Am I imagining this, because that’s your grandmother and I don’t want you to think …’