And so, as the Gravy Lake gets closer, and I can see the shapes of our companions gathering on its shore, I begin to exert myself a little more. I deliberately make my strides stronger and longer … but still Seb is ahead of me. I drop my weapons and pump my arms more, thrusting my chin out, and run harder. And harder.

It’s happening again. My dream is not doing what I tell it to do.

What’s wrong? I’m not gaining on Seb at all.

I have no idea exactly how fast we are running, but the ground is whooshing past under my feet at a terrifying rate and, however fast I go, Seb is managing to keep ahead of me.

It is not meant to happen like this. I don’t understand it.

Kobi and the others are in full view now, and I can’t stop in time. I’m going so fast that I run right past them and into the shallows of the freezing-cold lake where the watery school gravy finally stops me and I fall forward, sinking under the surface before rising, gasping for air. The others point at me and laugh, while Seb bounces on his feet, arms raised in victory.

The cold of the gravy has shocked me.

Being beaten by Seb has shocked me more.

I’m still standing in the shallows of the brown lake, and I look round at the group: there’s little Erin, old Farook and, of course, Kobi the Cave Boy who looks like he does in Seb’s book, which is cartoonish. He’s basically a walking, talking drawing. He is wearing a fur thing that only covers one shoulder and he has a club-and-rock weapon like the one I just ditched. Looking at his fur makes me feel even colder because I’m just wearing my soaking pyjamas. I close my eyes and say, ‘Change pyjamas to fur,’ and wait.

Nothing happens. I try again, but I’m already losing confidence.

Seb hasn’t seen any of this: he’s a few metres away, talking to the others. I call over to him and he saunters back, all cocky after beating me in a running race.

‘What’s up, loser?’ he says. ‘You not cold?’

‘Seb,’ I say, ‘it’s going wrong again.’

‘What do you mean, “again”?’ says Seb.

‘I’ve told you: the dream doesn’t always do as it’s told, and it’s happening much quicker now. Look!’ I point upwards. ‘Turn green!’ The sky does not turn green. I don’t want to scare him, though. Instead, I say, ‘Shall we wake up now?’ It’s really the only safe option.

He wrinkles his nose and pouts. ‘I don’t want to. What’s wrong with you? You said it yourself, Malky. We haven’t got much time. I want to get to the bit when I ride the mammuf, at least!’