I went and got the key from the dish. My hand, I noticed, was not quite steady.

It slid in like it had been waiting, the way a key does when it’s the right key, that particular silken give that has nothing in common with the grinding non-fit of a wrong one. I turned it. Something inside the mechanism gave a soft, oiled click, far quieter than I expected from a lock that old, which told me someone — Edith, it had to be Edith — had maintained it. Had oiled it. Recently enough that it still worked like new.

I pulled the little door open, and what I found made me sit down hard on the paint-spattered floor, because inside that space, no bigger than a shoebox, was not money, and was not jewelry, and was not a deed to some other house I’d never heard of, all of which I had, somewhere in the last two months, allowed myself to imagine.

It was a stack of letters, tied with white ribbon gone the color of old teeth, and on top of them, a photograph of a young woman who was not my grandmother, standing in front of this very house, pregnant, and smiling in a way I had never once seen Edith Calloway smile in forty-one years of knowing her.

I want to tell you that I opened the letters immediately, that I sat on that paint-flecked floor and read them straight through like something out of a movie. I didn’t. I sat with the photograph in my lap for almost an hour, just looking at it, because I needed, first, to understand what I was looking at, and the truth is I didn’t, not yet, except that the woman in the photograph had Edith’s chin and Edith’s stubborn, deep-set eyes, but was not Edith. Was younger than Edith had ever been in any photo I’d seen of her, even the ones from her wedding. Was wearing a dress that belonged to a decade before Edith was born.

It was, I would learn over the following days, my great-grandmother. Edith’s mother. A woman named Vivian, who I had heard mentioned perhaps four times in my life, always briefly, always followed by Edith changing the subject with the practiced ease of a woman who had spent sixty years changing that particular subject.

The letters were between Vivian and a man whose name was not my great-grandfather’s. They spanned three years, 1947 to 1950, written in a looping, urgent hand that pressed hard enough into the paper that you could feel the words on the back of each page like braille. They were not letters about nothing. They were letters about a man named Joseph, who worked the rail line that used to run through town before it was torn up in the sixties, and who Vivian had loved with a specificity and a heat that made me feel, reading them, like I was trespassing on something that had nothing to do with me at all.

Except it did. Because in the eleventh letter, dated September of 1949, Vivian wrote to Joseph that she was carrying his child, and that her husband — my great-grandfather, a man named Calvin Reyes who I knew only from a single dour photograph on the parlor wall — did not know, and that she did not know what she would do.

That child was Edith.

I sat with that for a long time. Longer than I’d sat with anything in my life, I think, including the morning I got the call that Edith had died in her sleep, eighty-nine years old, in the bed not ten feet from where I was now sitting with her secrets in my lap.

The rest of the letters told me the rest of it, in pieces, the way letters do, because they were never written to explain themselves to a stranger forty years later. Joseph had wanted Vivian to leave Calvin. Vivian, it seemed, had wanted that too, in the aching, useless way you want a thing you’ve already decided you can’t have. There was a last letter, shorter than the others, dated the spring of 1950, in which Joseph told her he was being transferred to a rail yard three states away and that he would wait for her if she would come, and that if she didn’t come by the first of June he would understand, and would not write again.

There was no twelfth letter. Whatever Vivian decided, she decided it without writing it down, or she wrote it down and it never made it into this box.

What was in the box, instead — beneath the letters, which I almost missed because by then my hands were unsteady and I was not being careful — was a single sheet of paper in handwriting I recognized instantly, because it was the same hand that had labeled every spice jar in that kitchen for forty years. Edith’s hand. Dated eleven years ago, which would have made her seventy-eight when she wrote it.

To whoever finds this — and I expect it will be you, Margaret, because you are the only one who ever asked me real questions instead of comfortable ones —

My mother kept these for forty years in a hatbox in her own closet, and gave them to me three weeks before she died, because she said a secret that dies with you isn’t honesty, it’s just hiding with better timing. I have kept them for thirty-one years since, trying to decide if she was right.

I am not going to tell you what to think of her. I have spent half my life angry at her and the other half grateful, and I have never managed to settle on one feeling longer than a season. What I will tell you is this: Calvin Reyes raised me as his own and never once, not in word or look, made me feel like anything less than his daughter, and I loved him for it the way you love a person who chooses you on purpose, every day, instead of by accident of blood. I do not know if Joseph ever knew I existed past that last letter. I never tried to find out. There were years I wanted to, and years I was glad I hadn’t, and I could not tell you, even now, which years were the right ones.