She branches a new line of sugar off the main one. ‘So this new life – in Finland, or hobbling around with two broken legs – this is your life now. But! What if you hadn’t moved countries or if you didn’t fall from the trapeze and break your legs? How would that old life have turned out? You never know, do you? Except that you can use a magic spell to jump over to that old life, and see how things would have turned out …’

I stare hard at the lines of sugar, but they don’t help me make sense of what she just said. My mind’s struggling to wrap itself around this idea that there are different versions of our lives, all carrying on at the same time, parallel to each other. I mean, I know that magic is, well … magic. But it’s as if everything I know about life and how it works has been tossed out the window.

‘Anyway, Merry’s gone to one of those other lives,’ says Sylvie briskly. ‘A life she might have lived had she made a different decision.’

‘But …’ I say. ‘What decision? What life?’

‘Who knows?’ Sylvie brushes an ant off the table. ‘We all make lots of new branches, or parallel universes, every single day. We make a new branch when we chat to a stranger and it turns out to be someone who changes our life, or we miss having a car accident because we slowed to look at a sunset. Even small moments can change the course of your life. Merry might have gone back to a life where she never met you, Dave, for instance.’

A life without Dad in it means a life without me. The thought makes me feel a bit woozy.

‘Right,’ says Dad, sounding annoyed. ‘Thanks for coming up with that particular example, Sylvie.’ He runs a finger across the tabletop, making a dent in the line of sugar. I don’t like him wrecking the sugar-line. I know it’s silly, but I’m afraid it might – somehow – wreck that universe where Mum is.

‘So are there parallel universes for ordinary people, too?’ I ask. ‘I mean, non-magicians.’ I glance at Dad.

She nods. ‘Yes, of course. Everyone makes decisions that lead their life in other directions. Everyone.’ She points to the waiter. ‘Him. All those people out there shopping. But magicians are the only ones who can visit their parallel universes. They have twenty-four hours to get themselves back to their home universe. If they don’t come back within that time, another magician must bring them back.’

So Thelma was right. And the twenty-four hours are up.