It covered most of Ash House garden, and it was lightning, but not like any lightning ever in the history of the world. A vertical sheet of it stretched from the ground to the sky, as far up as I could see, a bright white wall, buzzing and crackling like it was alive.

Whizzy dived towards it, away from us, then turned back, all confused.

‘Whizzy!’ I cried, breaking away from Sam and racing towards the hissing wall of light. If Sam shouted after me, I didn’t hear him.

The lightning wall renewed itself again and again, and this close, the noise was deafening. Sparks spat and popped, and underneath it all, there was a deep hum, like fifty electricity pylons.

Whizzy dipped and bucked towards me, as ripply and unsteady as she’d been that first night. My hands prickled. My teeth tingled and fizzed, but I smiled.

We gazed at each other.

‘Whizzy,’ I said. Her name came out of my mouth as a colour: bright orange particles, like light from a sparkler. I laughed, and the laugh rose like bubbles in a glass.

I stopped laughing. I said, ‘You know you need to leave, don’t you? Before someone else gets hurt? And before they hurt you.’

Her sunhorse head lifted and my heart felt wobbly. I tried to swallow the sadness, but it wouldn’t go down.

‘Find a magnetic tunnel, Whizzy. Be safe.’

Her head dipped. She turned a full circle one last time – golden, shimmering, beautiful – and I realised Sam was beside me.

Then she dived into the lightning and became a stream of light speeding towards the sky, almost the same colour as the lightning itself, but even brighter, weaving and billowing through it and away.

Like a huge dying firework, the lightning wall gave up. It collapsed, went phut and spilt over and into itself, fizzling out into nothing but a powdery charcoal trail.

When Sam spoke, his voice was all echoey and weird. ‘She’s gone.’

We stared at the mess of blackened earth where the weeds used to be. Whizzy had gone upwards, but it felt like I was falling in the opposite direction.

‘Hope she finds the way,’ I said to Sam, but I couldn’t look at him, not with my wet eyes.

He didn’t reply. When I gave him a quick sideways glance, he was nodding and biting his lip. After a while, he said, ‘The tunnels are probably in a good phase.’

‘Yeah,’ I said. ‘She’s clever. She’ll get back OK.’

But we didn’t have long to think about it. We’d only been walking for a minute when they appeared: two men, one of them someone’s dad from school, I think. Behind them came a couple of younger kids I’ve never met, then an older couple from Malusky’s Corner.