Four days ago, I hid a small tape recorder in a bookcase at about five minutes before the hour when our sitter was due to arrive. His name is Justin, and he is a student at the university where I myself am working toward an advanced degree. He is friendly, likeable. Little clouds of sparse beard appear at his jaw, above a choker of painted red beads. From wide-spaced eyes the color of tea comes a warm and steady light.

I have nothing against Justin. A responsible father, however, must ask: what leads a boy of his age to want to sit for a six-month-old girl?

"Good money," was the response of my wife, Sherrene. "Same reason the others called."

"The others were girls," I said.

"Were they girls?" she sang, nose to nose with our daughter, Josie, who produced bubbling laughs. "Were the other ones girls?"

It was not yet dawn. Sherrene was dressing for work. She had slipped on a skirt and blue hose that had gone transparent at the heel and sole. In order to reach Josie, whom we had propped up in our bed, she'd let herself fall and bounce.

I was still in my nightclothes, a T-shirt and boxer shorts. I was standing. I said, "Why not a girl?"

As Sherrene rose and then frowned into the mirror at her dresser in order to brush out her hair, our daughter began fussing.

"Did you not say you thought I should make the decision?"

I told her I had.

"I called all of his references. Two separate people said to me, Justin, he's wonderful, he's part of the family. Justin, we love him."

Hoisting our daughter up into my arms, I said, "Hey. It's your Daddy. Don't cry."

"I wasn't looking for a guy sitter."

I said, "Why do you cry with me, Josie?" I said, "I think she wants you."

This was a week ago, maybe three days before I hid the recorder behind a half-row of books.

I've been listening to the tape. Much of it sounds exactly how one might expect—accidental. A faraway drawer will slide open. A toy will beep a few bars of a waltz. Then nothing. Things stir but recede immediately into the faint gush of passing time.

But a portion of the tape has drawn my attention. I've transferred it onto my laptop, where it can be played as a continuous loop.

She is laughing, Josie, and continuing to laugh. When she breathes, another sound can be heard, much lower—the laughter of Justin.

In all of the ways I have pictured the scene, there is no cause to fear for her welfare. Still I replay it. After Sherrene has kissed me goodnight, I reach for the laptop, lower the sound, and open the audio file, which I have given the name "clip2."

Josie laughs, then doesn't, then does. It is like a tiny, bouncing wheel. At points it slows down, and the broader of the two laughs seems to rise, Justin's. His is steady, unpunctuated. It escapes him as freely as breath.

I try to be a good person. Honest, considerate. I try to work hard, so I can finish this degree, so I can start earning money, so we can be more secure.

I try to be who I should be, for Sherrene, for our family.

The question, adrift in the midnight stillness, ineluctable: have I failed?