‘No!’ shouts Erin and takes a step towards the men, but their spear points stop her in her tracks. The leader says something to the dogs and they gather round him without taking their amber eyes off us. Meanwhile, he grabs Seb’s wrists and starts tying them together with a rough rope made of vines. His big arm muscles flex beneath his skin and I see a rough, smudged tattoo of a swastika through the hair.

I’m properly scared now. ‘Wake up!’ we both shout again.

The tall man bares his teeth and steps towards me, leaning close enough so that, when he laughs, I can smell his stinking breath.

‘Too late,’ he says. ‘You didn’t listen to the warnings, did you? Try it again, strange, modern pyjama-boy, ha ha!’

‘Wake up!’ I shout for the third time, then I do the hold-my-breath thing, releasing the air after a few seconds with a paaaah! right in his face.

He sniffs my breath then sneers, ‘Toothpaste, hm? Yet you’re still here. That’s reassuring. To me at any rate. Welcome to my world – a vast dimension filled with anything you can imagine. But unfortunately for you – I can imagine too.’ He draws himself up to his full height – enormous now – and addresses his companions. ‘Take the little one away!’

‘No! Malky! Stop them! Wake me up!’

‘I can’t, Seb, I can’t! Do the breath thing! Wake up!’

Seb’s cheeks are bulging, but then I have to look away as the dog with the damaged leg lurches unsteadily towards me and I have no choice but to run.

This is just a dream, I keep telling myself. What’s the worst that can happen? Seb will wake up naturally soon.

I run through the line of trees, pursued by the dog, my chest aching with fear and breathlessness, until I reach the clifftop and I turn round to see the huge grey-muzzled beast hurtling towards me. Below me is …

Nothing at all.

Not sea, not rocks, not a canyon, not even something silly and dreamlike, like a trampoline or a big pile of autumn leaves: just an endless, grey, fuzzy emptiness like a television that is not tuned in to a channel. It is as though Dreamland has just given up trying. As I look back, the dog is in the air, its front paws stretched out, and they hit me – oof! – straight in the chest, sending us both tumbling into the greyness.

I start to shiver: a small trembling that becomes a shake. My teeth are chattering and my whole body begins to twitch in huge convulsions; my stomach starts to spasm and I feel as though I’m going to throw up, and I grip the sides of the white toilet bowl and up it comes.

And again.

And again.