Whizzy corkscrewed slowly around the arrow on the Slide to Unlock bit, and a tiny noise vibrated through the phone. I brought it closer to my ear, and it was awesome – musical – but Whizzy was whirling too fast, so sound and picture were both blurred. She was just playing. Playing in my phone.

This felt fantastic. Now Sam could see her properly and – I caught my breath – this was going to solve everything.

I ran over to Sam.

‘You were right, Sam! You were dead right!’ I said. ‘The compression and unzipping along wires, and all that other science stuff you said – she’s done it! Whizzy’s in my phone! Come on!’ And I ran back over to my patch of grass, hoping he’d follow. Surely he had to forgive me now?

He did follow. He was slow, and looked confused and annoyed, but he came.

I shoved the phone right up to his face, so close that he flinched. ‘Look at this!’ I said, and I edged round so I could see too. The entire screen was rippling. Brilliant white ridges ran across the top half, then fizzed down to nothing but a tiny S shape against a grey background: Whizzy. She was small, in the bottom-right corner under the mail icon, but growing.

Sam’s eyes were the brightest I’ve ever seen them. ‘What happens when you tap her?’ he whispered.

I did, gently, and a blizzard of white dots poured out over my finger. She disappeared. I swiped across and there she was, swirling all over the place leaving trails of pink light, electric-looking, like a plasma lamp I once had.

Whizzy grew and grew. The icons were mostly blotted out.

Sam didn’t move. He just stared. ‘Wow, Alfie,’ he breathed. ‘Incredible. Like a dream.’

I nodded. ‘But we’re awake!’

His mouth was stiff with surprise and stayed open a bit, as if he was expecting a spoonful of food.

‘Do you think she travels like a text?’ I asked him, still speaking just above a whisper. ‘And where do you think she actually is? In the screen, or bombing about in the circuit board?’

He shrugged and raised his eyebrows, as if surprised I’d even heard of such things.

‘Dad told me how a smartphone works,’ I said, staring down at Whizzy. ‘How do you squash up so small?’ I whispered to her. ‘And you’re quiet now. Must be getting used to it.’

‘Such eyes,’ he said. ‘They are like mirrors. And you were right – she is like a sunhorse. A total sunhorse.’

‘I’ll have to tell Mr Clemm she’s in here,’ I said. Sam looked at me. ‘But not just yet.’

‘Should I text you? To see what happens?’

I nodded and he raced to get his phone. When the text arrived, she shrank again, dived on to it and rode away as it scrolled off-screen.

‘I’ve lost her!’ I said.