‘Wake up!’ I shout again.

I take a huge lungful of air. Then I tighten my mouth and throat shut and try to breathe out. My cheeks bulge. I strain harder, urging my ears to pop with the effort.

Meanwhile, the crocodile chews down deeper, his teeth inching further up my arm towards my shoulder. With my other hand, I pinch my nose and blow hard, feeling my eyes and cheeks bulge until I release the air with a loud paaaah!

Then I open my eyes.

I’m in bed, panting hard, still imagining that my arm is being eaten by a crocodile. I know now that, if I close my eyes, the images from the dream will come back to me for a few seconds before fading away. So I do, just to test it.

And there’s the croc, jaws clamped on my wrist, and a shooting pain goes up my arm until I open my eyes again and the croc has gone.

I am awake, in my own bed. I turn my head and there is Seb, fast asleep in his.

Except my arm is still hurting. Not badly. Not a-crocodile-is-biting-my-arm-off agony, but it’s definitely sore. I wait a moment until my breathing returns to normal, and look up at the Dreaminator above me.

No more nightmares! the instructions said. Even when I was little, and before Mam and I had renamed the crocodile Cuthbert, the thing had never actually bitten me. I swing my legs out from under my duvet and shuffle out of bed.

I turn the bathroom light on and have a wee, and I roll up my pyjama sleeve to look at my arm. The pain is lessening, but it’s still there and … am I imagining this? I look closer.

Surely not.

There is a line of indentations, little pink marks, where the croc chomped down. Exactly where its teeth were. Turning my arm from side to side, I can see the marks clearly. Then I hear a noise on the landing outside and the rattle of the bathroom doorknob. It’ll be Seb coming for a drink of water.

I’m facing the mirror, which reflects the bathroom door behind me.

The door opens slowly, creaking a little. I look in the mirror and get ready to say hi to Seb, but there’s no one there. That’s odd: it looks like the door is opening by itself.

I don’t want to turn round. I don’t want to see what is opening the door, because it has to be at ground level, but I force myself to look …

… and he’s there, on the ground, raised up on his squat legs. He’s half in and half out of the bathroom door. The massive crocodile takes two tottering steps towards me across the tiles and I scream, ‘No!’ as it opens its jaws wide, and slowly closes them again.

Then from within the beast comes a grating, hollow growl, like an empty metal bin being dragged across rocks. The croc’s mouth opens slightly and it sneers in a deep, upper-class drawl like a British army officer in one of Fit Billy’s war movies.

‘I say. Look who it is. Hello, Malcolm!’

How can this be? In my terror, I scream out for Mam, and back myself up against the sink as the croc inches forward.

‘Mam! Seb! Maaaam!’

Cuthbert’s at my feet now, and I hoist my bum on to the edge of the sink to raise myself off the ground. I kick out at the advancing beast and I can see the shine on his teeth as he slowly closes his mouth and lowers himself on to his belly, bending his back half until he has cleared the door, then using the weight of his knobbled tail to slam the bathroom door shut, completely blocking my escape. He is clearly willing to take as long as he likes.

‘Mam!’ I shout again. ‘Maaaam! Help!’

‘Aw – calling for mummy, are we?’ Cuthbert sneers. ‘It won’t do you any good, you know.’

The croc blinks at me patiently, and runs its tongue round its teeth like it’s sizing up its next meal. I scrabble further up the edge of the sink and search with my hands for things to throw. A nailbrush pings off its snout, a glass, a toothbrush, then I glance at the tube of toothpaste in my hand. The name looks strange.

CLOGAET

Then the letters seem to move.

LOGTACE

Wait. What? Why doesn’t it say COLGATE?

Something comes back into my head. I remember reading the instructions for the Dreaminator.

Numbers on clocks and printed words are usually jumbled or indistinct during dreams.

Crocodiles don’t talk, or blink for that matter. They don’t have tongues, either, not the sort you can stick out, anyway.

This just cannot be happening.

I am still dreaming.

‘Wake up!’ I shout. ‘Waaake uuuup! Wake up! Oh, please wake up!’ As Cuthbert lunges forward for an attack, I kick out wildly, desperately, sobbing and shouting and trying my hardest to recapture the breath that seems to have been forced from my lungs.

And I’m back in bed, with my duvet twisted round my legs, thrashing out at …

… nothing.