But they did something else, too. This is what I could not say, and still will not be able to say fully, not for some time. What I can tell you is that in the months prior to the wedding, something had been on my mind at work, something involving the group within the company that worked on investment securities. I could not understand the returns this group was producing so consistently. I could not understand how the math worked, though I did not expect to find anything untoward. Initially, I think I might have been looking for some kind of game to play, something that could connect me to the math I grew up loving so much. As you may have gathered, I have not felt connected to that in a long time. So here was a problem in front of me, and I could only find the solution by trying, again and again, to work backward—to reverse engineer the numbers. At first it was challenging, the most challenging math I had done in ages, and I enjoyed working on it.

Eventually, though, I realized that it was not, in fact, challenging math. It was impossible math. I could not understand the numbers because the numbers did not make sense. I cannot say here to whom I brought this information first. What I can say is that, initially, I was told that I had only uncovered a simple mistake, one that I was assured would be fixed.

Once, you told me that when you are feeling most inspired, you see letters sketch themselves in your mind all the time—at night when you’re falling asleep, first thing in the morning when you wake, when you’re walking or waiting for the train or cooking or eating. I suppose that’s the closest way of describing how I felt, for weeks afterward. In the pool, I could see the numbers in my head. I could picture them, swimming along as smoothly as I was, except every once in a while, a splash, a missed stroke.

So that word, “mistake”—it stuck with me, even as I wanted to trust what I had been told about it being fixed. It stuck with me even after Avery and I split up, after I’d tried to convince myself that the code in the program was only about our relationship. It stuck with me enough that I checked the math again. It stuck with me enough that I agreed, at a certain point, to check these numbers as part of a larger investigation, about which I can say no more here.