‘Kind of,’ Sandra said. ‘I like her – she’s a lovely girl – but I can’t bear the thought she might hurt him. I want him to be in love and happy, but I don’t want him to be vulnerable. And teenage boys in the grip of their first love are the definition of vulnerability.’

‘I think we have no choice but to let it go,’ Martin said. ‘We can’t protect him from everything. I will talk to him though, about Maggie and the anniversary.’

‘OK.’ Sandra looked at him, her expression suddenly serious. After a pause, she spoke. ‘Do you think she’s alive?’

‘You know,’ Martin said, slowly, ‘I think about that all the time. All the evidence says she isn’t. I’ve read everything, all the statistics about the likelihood of someone turning up alive after one day, two days, a week, a month, and they’re pretty clear: she’s more than …’ His voice broke, and he looked away. ‘More than likely dead. But some part of me is convinced she isn’t.’ He looked at his hands. ‘But sometimes, when I think of where she might be, I wonder whether she would be better off if she was.’

‘Don’t say that,’ Sandra said. ‘If she’s alive – wherever she is – that’s better than the alternative. Because if she is alive, she’ll come back to us. One way or another, she’ll find a way to come home.’

Martin caught her gaze. ‘I hope so,’ he said. ‘I hope so.’

3

James looked at the equation. Mr Best – he insisted on being called that – had finished explaining how to do it, and for a moment he’d understood, but it was already gone. He shook his head.

‘I don’t really get it,’ he said.

Best was sitting on the other side of the dining room table.

‘Let’s forget that specific example,’ he said. ‘And talk about what quadratic equations are used for.’

‘OK,’ James said.

‘Let’s say you kick a football. It goes up and forward and then starts to come down until it’s still. A quadratic equation can tell you the height of that ball at any time.’

‘I don’t need it to,’ James said. ‘I can see the ball.’

‘What about a missile? You can’t see a missile.’

‘I don’t want to fire a missile.’

Best smiled. ‘Very admirable, but if you did, a quadratic equation would be very useful. It’s like probability. Which do you think is more likely to come up in the lottery? Six sequential numbers – like four, five, six, seven, eight, nine, or six unconnected numbers?’

‘Unconnected.’

‘No,’ Best said. ‘It’s exactly the same.’

‘So I should pick sequential numbers if I do the lottery?’

‘Pick any numbers you like.’

‘What would you do, if you won the lottery?’ James said. He was desperate to change the subject.