‘Quick!’ His voice had gone deep and booming. ‘Wish we were lighter than air, or we’re goners!’

‘I wish we were lighter than air!’

Oh, the relief! The sweet merciful life-saving relief as I floated up off the ground! The horrible weight of my head that felt like it was going to break my neck was gone, my limbs were light and free, and the ground was no longer a terrifying enemy that was about to kill me, but a nice wide stretch of green grass that looked peaceful and friendly as I gradually rose above it.

The people on the Common were all pointing up and staring, shouting and jabbering, unable to believe their eyes.

‘Whew!’ Evan said. He was hovering just a few metres away. ‘That was close!’

‘What happened?’ I couldn’t figure it out. ‘Why did we get so heavy? I didn’t wish for that!’

Evan’s like, ‘I should have thought of it. Of course when you get bigger you get heavier!’

‘Yeah, obviously, but I still don’t get it. If we’re bigger all over—’

‘That’s the problem. The thing is, we got bigger in three dimensions. So we’re over ten times taller than before, but more than a thousand times heavier.’

‘But what about dinosaurs? They were giant, and they could walk about OK.’

‘Yeah, but they’d evolved to be like that. Their skeletons were built to hold their weight. We’re not the right shape to be so big, we weren’t designed for it.’

All this time we’d been drifting upwards. Already the ground was far away. The Common now looked like a green spot in the middle of a big grey town. People looked like ants and cars were like little beetles. And it was getting cold. Like, really cold. What my dad would call brass monkeys weather.

‘It’s freezing!’ My teeth were chattering. And you can imagine the racket that made, when each tooth was about the size of an iPad.

‘We’re gonna keep rising ’cause we’re lighter than air!’ His teeth were going like a set of giant castanets as well. ‘And it’s gonna get colder and colder and soon we won’t be able to breathe. You have to do something!’

‘OK, OK, I get it!’ I thought for a second. ‘Right, I wish we were heavier than air, but only a bit heavier. I want us to be able to walk around OK. And also I wish we don’t tread on anyone or squash anyone, all right?’

We started to sink, quite fast, but not scarily fast. It was like dangling from a parachute. Or that’s what I’d guess, anyway, seeing as I’ve never done a parachute jump. The air got warmer again. My giant goosebumps disappeared.