1 | The Slap Heard Through the Glass My name is Elena Marsh, and for a long time I told the story of that night as if I were the villain of it.

The flute section kept playing for a few seconds past the moment.

Richard said my name, low, the way he used to say it when he wanted me to smile for a photograph.

He did not ask me what was wrong.

He did not ask who the woman was.

He turned his shoulder to me and put his back between the woman in white and the rest of the room.

I remember looking for one face in that crowd.

My best friend Nora was flying back from a deposition in Chicago and had not landed yet.

My mother is gone.

My father is gone.

I looked around a room full of two hundred people I had known for a decade and not one of them stepped forward, and I understood in that second that I had been optional to every single one of them.

I let go of her arm.

I did not cry.

I walked toward the entry table by the elevator, where the caterers had set down the handbags and the wraps, and I picked up the small beaded clutch sitting on top of the stack.

I knew the moment my fingers closed on it that it was not mine.

Mine was black, satin, sitting at home on my dresser.

This one was covered in hundreds of tiny seed beads and it felt warm in my hand, like it had been held all evening, like it had been set down only seconds before.

I did not put it back.

I walked into the elevator.

I pressed the button for the lobby.

On the way down, the elevator was so smooth that the only sound was the clutch buzzing softly in my hand.

Somebody was calling it.

Somebody had been calling it all night.

When the doors opened on the ground floor, I stepped out into the marble lobby, and I sat down right there on the polished floor in front of the doorman, my back against the cold stone wall, and I looked up at the ceiling of a building I was supposed to be married inside of in six weeks, and I thought to myself, Elena, what in the world did you just pick up.

2 | The Coat Pocket
I did not go back upstairs.

I did not call Richard, either.

I sat in the back of a cab and let the doorman hand me my own coat like I was a guest at my own party, and I told the driver my address, and I watched the light from the penthouse windows slide off the glass as we pulled onto Third Avenue.

When I got home, I locked the door, took off the green dress, and hung it up, because I did not know yet whether I was going to need it again.

Then I sat down at my kitchen table with the clutch.

It opened with a small click.

Inside there was a phone I had never seen.

Not a phone case, not a spare, an entire phone, charged, turned face-down, still buzzing with text messages.

The screen lit up while I was looking at it, and I saw a name I did not know.

Then I saw the message preview, and I saw my fiancé’s first name at the top of it.

I did not read the messages.

I am telling you this because people always ask me if I read them that first night, and the answer is no.

I closed the clutch.

I got up and made myself a cup of tea and I sat back down and opened it again, and the second time I found things I had not felt the first time, because the first time I was only looking for the phone.

There was a folded receipt.

A wire transfer, forty-eight thousand dollars, drawn from an account number I did not recognize, dated eleven days earlier.

And there was an invitation.

A real one, printed on heavy paper, cream colored, embossed at the top with a small crest.

It was in Richard’s handwriting.

The names on it read “Mr. and Mrs. Richard Coyle” and then a name that was not mine.

I sat with that invitation in my hands for a long time.

I want you to understand what I thought I already knew.

Two weeks before that night, I had found a photograph in the inner pocket of Richard’s coat, a woman on a beach, blonde hair pulled back, looking at the camera with a relaxed smile.

And when I found it, I did what any woman does.

I made up a story that let me keep my life.

I told myself he had an old girlfriend.

I told myself it was a client.

I told myself nothing, and I put the photograph back in the coat, and I hung the coat up, and I went into the kitchen and asked him what he wanted for dinner, and he said salmon, and I made salmon.

That is the part I am most ashamed of, if you want to know the truth.

Not the grabbing.

Not the walking out.

That.

The salmon.

At around eleven thirty my best friend Nora let herself in.

She had come straight from the airport with her suitcase still in the hall, and she had heard the whole thing from two different people before her plane even landed.

She is a divorce attorney, forty-four years old, and she has spent her entire adult life watching people find out who they married.

She sat down across from me, took the invitation out of my hands, and read it twice without saying a word.

Then she said, “Elena, this is not an affair.”

I said, “What is it, then?”

She said, “This is planning.”

She laid the receipt next to the invitation and put the phone face-up between us.

She did not read the messages either.

She just looked at the screen, at the name at the top of it, and then she flipped the invitation over to the back, where the date was printed in small gold numbers.