In retrospect, it was the realisation that if I had claimed to be ill I would have been let off the flight that pushed me to the line between sanity and meltdown. It came on top of the stress of the previous day’s life-threatening emergency, my failure to save my marriage, administrative incompetence and gross invasion of personal space. One more deception, a small deception, and I could have walked off. But I had reached my limits in all dimensions.

I couldn’t walk away. I was being prevented from walking away.

I closed my eyes and breathed deeply. I visualised numbers, alternate sums of cubes behaving with predictable rationality, as they had before humans and emotions, and as they would for all time.

I was aware of someone leaning over me. The flight attendant.

‘Excuse me, sir, would you mind bringing your seat fully forward for take-off?’

Yes, I would fucking mind! I had already tried and it was broken, and the almost zero probability that it would make any difference to anyone’s survival…

I breathed. In. Out. I did not trust myself to speak. I felt the steward reaching across my neighbour, jiggling my seat as the meltdown began, and the seatbelt prevented me from moving. I could not let this happen in front of Rosie.

I started my mantra, steadying my breathing again and keeping my voice toneless. Hardy-Ramanujan, Hardy-Ramanujan, Hardy-Ramanujan.

I don’t know how many times I said it, but when my mind cleared, I could feel Rosie’s hand on my arm.

‘Are you okay, Don?’

I was not, but the reason had reverted to the original problem. And I had a further five hours to find a solution.

36

‘Don, I have to sleep. I’m not going to change my mind between here and Los Angeles. I really, really appreciate you trying. I’ll call when I get home. Promise.’

Shortly after Rosie put her seat back and closed her eyes, the steward returned and offered our neighbour an upgrade. I assumed the seat would remain vacant: I was accustomed to having empty seats beside me, except on full flights, as a result of my special status with the airline. A win-win outcome for my neighbour and me. But he was replaced by another male, estimated age forty, BMI twenty-three.

‘I guess you’ve figured out who I am,’ he said.

Perhaps he was a celebrity who expected to be recognised—but I doubted that celebrities travelled in economy class. I provisionally diagnosed schizophrenia.

‘No,’ I said.

‘I’m a federal air marshal. I’m here to look after you—and the rest of the passengers and crew.’

‘Excellent. Is there some specific danger?’

‘Maybe you can tell me that.’

Schizophrenia. I was going to have to share my flight with a mentally ill person. ‘Do you have ID?’ I asked. I was trying to distract him from his delusion that I possessed special knowledge.

To my amazement, he did. His name was Aaron Lineham. As far as I could tell from approximately thirty seconds of close examination, the ID card was genuine.

‘You got on the plane with no intention of travelling, am I right?’ he said.

‘Correct.’

‘What was your purpose in boarding the flight then?’

‘My wife is returning to Australia. I wanted to persuade her to stay.’

‘That’s her, in the window seat, right?’

It was definitely Rosie, making the low-level sleeping noises that had begun during the baby-development project.

‘She’s pregnant?’

‘Correct.’

‘Your kid?’

‘I presume so.’

‘And you couldn’t persuade her to stay with you. She’s leaving you for good and taking your kid?’

‘Correct.’

‘You’re pretty unhappy about that?’

‘Extremely.’

‘And you decided to do something about it. Something a little crazy.’

‘Correct.’

He pulled a communications device from his pocket. ‘Situation confirmed,’ he said.

I guessed that my explanation had been satisfactory. He was silent for a while, and I looked beyond Rosie into a clear sky. I watched as the wing dipped and centrifugal force held me in my seat. Without the horizon as a reference point I would not have known the plane was turning. Science and technology were incredible. As long as there were scientific problems to solve, I still had a life worth living.

Aaron the Marshal interrupted my reflections.

‘Are you afraid to die?’ he asked.

It was an interesting question. As an animal, I was programmed to resist death to ensure the survival of my genes, and to be afraid in circumstances that threatened pain and death, such as a confrontation with a lion. But I was not afraid of death in the abstract.

‘No.’

‘How long do we have?’ asked Aaron.

‘You and me? How old are you?’

‘I’m forty-three.’

‘Approximately the same age as me,’ I said. ‘Statistically, we both have approximately forty years, but you appear to be in good health. I am also in excellent health, so I would add five to ten years each.’

We were interrupted by an announcement. ‘Good afternoon. This is the first officer. You may have noticed the aircraft turning. We’ve had a minor problem, and air-traffic control has asked us to return to New York. We’ll be commencing our descent into JFK in approximately fifteen minutes. We’re sorry for any inconvenience, but your safety is our first priority.’