The walls of Deadman’s Cave are absolutely covered with pictures; paintings that seem to move like a flick book in the jittering light.

The lightning fades again. But I have to see more! I tear off Dad’s backpack and rummage about; I find his torch and click the switch.

‘Oh, Dad!’ I hiss through my teeth. The battery’s dead, of course. Mum’s always telling Dad off for not changing the batteries on things. ‘For goodness sake, Dad, you total banana!’ I bang the torch on my hand. It flickers to life, a thin, pale beam, but it’s enough. I hold the torch high and peer all around me at the painted walls of Deadman’s Cave.

They’re not just pictures, they’re pictures that tell stories: there’s a hunter who bounds long-legged in a leap. The hunter’s chasing a red deer, a hart with massive antlers, and the deer’s fast too, I can feel the strength of its muscles in the curve of the line. And there’s another deer ahead, a young one, smaller antlers, less strong, less sure; he’s looking back over his shoulder. But the young deer doesn’t see the hunter or the spear, the spear that’s arcing from the hunter’s empty hand, straight towards the deer’s panicky heart. ‘Spea!’ I murmur. The torch fades and goes out.

‘Come on!’ I bang the torch on the cave wall. I want to see more. Trembly thin light wavers through the gloom.

‘Wow!’ I whisper, walking a few steps deeper into the cave, forgetting myself at the sheer wonder of it. These walls are alive with eagles that swoop and fish that leap. I see lynx and bear and elk and wolf and other animals whose names I don’t even know. Living pictures of creatures long gone from my Mandel Forest. And there are more people, people just like the boy with wild hair and animal skins, clutching spears in quick, strong hands. ‘Chauvet!’ I whisper. ‘Lascaux.’ Because I’m remembering the pictures in The Wild; photos of famous caves in France with paintings just like these ones, thousands and thousands of years old. ‘Stone Age paintings,’ I murmur as my torch fizzles out properly. All is blackness. Outside thunder booms.

I can feel the truth sitting beside me in the dark, watching me, waiting, daring me to meet its stare.

‘I’m in the Stone Age, aren’t I?’ I whisper; I’m breathing quickly. The air is cold; it tastes of damp and moss and mushrooms; the cave drips steadily like the ticking of a clock. ‘I’m in the Stone Age.’ A tingle of fear and excitement surges through me.

‘And you,’ I breathe, squinting through the dim at the vague outline of the boy’s sleeping shape. ‘You’re from here. You’re … you’re a real Stone Age boy.’ I shudder and I giggle and I hiccup all at the same time; my insides fizz and my brain spins.

Then I hear something. A new something. I slowly turn my head and I listen. There’s a noise coming from way way back behind me, right in the depths of Deadman’s Cave.