‘For something like Mrs Tachyon’s trolley?’

‘Try to pay attention, will you?’

‘Sorry.’

‘Haven’t you ever wondered what’d happen if a flying saucer landed in your garden? Or you found some sort of magical item that let you travel in time? Or some old cave with a wizard that’d been asleep for a thousand years?’

‘Well, as a matter of fact I did once find an old cave with—’

‘I’ve read books and books about that sort of thing, and they’re full of unintelligent children who go around saying “gosh”. They just drift along having an adventure, for goodness’ sake. They never seem to think of it as any kind of opportunity. They’re never prepared. Well, I am.’

Johnny tried to imagine what’d happen if Kirsty was ever kidnapped by aliens. You’d probably end up with a galactic empire where everyone had sharp pencils and always carried a small torch in case of emergencies. Or they’d make a million robot copies who’d fly around the universe telling everyone not to be stupid and forcing them to be sensible.

‘This is obviously something very odd,’ she said. ‘Possibly mystic. Possibly a time machine of some sort.’

And that was the thing about her. She arrived at an explanation. She didn’t mess around with uncertainty.

‘Didn’t you think that?’ she said.

‘A time machine? A time shopping trolley?’

‘Well, what other explanation fits the facts? Apart from possibly she was kidnapped by aliens and brought here at the speed of light, which is something they do a lot for some reason. But there might be something else, I’m sure you’ve thought of it.’ She glanced at her watch. ‘No hurry,’ she added sarcastically. ‘Take your time.’

‘Well …’

‘No rush.’

‘Well … a time machine’d have flashing lights …’

‘Why?’

‘You’ve got to have flashing lights.’

‘What for?’

Johnny wasn’t going to give in.

‘To flash,’ he said.

‘Really? Well, who says a time machine has to look like anything?’ said Kasandra in a superior tone of voice, or at least an even more superior voice than the one she usually used. ‘Or has to be powered by electricity?’

‘Yo-less says you can’t have time machines because everyone’d keep changing the future,’ said Johnny.

‘Oh? So what’s the alternative? How come she turned up with this new old newspaper and all these new old pickle jars?’

‘All right, but I don’t go leaping to great big conclusions!’

In fact he did. He knew he did. All the time. But there was something about the way Kasandra argued that automatically made you take the other side.

He waved a hand at the trolley.

‘I mean,’ he said, ‘do you really think something could just press the … oh, the handle, or the bags or something, and suddenly it’s hello, Norman the Conqueror?’

He thumped his hand down on a black bag.

The world flashed in front of his eyes.

There was concrete under his feet, but there were no walls. At least, not much in the way of walls. They were one brick high.