“In the 1990s, physicists started running high-tech experiments to figure out how neutrons broke down into protons. That in itself wasn’t so special—it’s the core concept behind radioactivity. But weird things happened.”

He pauses, so I smile and give him a thumbs-up.

“Neutrons that were created in particle beams—”

“What’s that?”

“It’s a particle physics thing, a nuclear reactor that shoots out billions of—”

“Never mind.”

“Anyway, neutrons created in particle beams lasted approximately fourteen minutes and forty-eight seconds before breaking down into protons.”

There are over a million Google results for “Thane Bernard.”

“But neutrons that are put into a lab bottle break down a little faster. Fourteen minutes and thirty-eight seconds,” Brian says.

Add “France” to that search and the results drop to five hundred and thirty-seven thousand.

Bernard is the second most common surname in France.

“I know what you’re asking yourself.”

Was Thane even French, or was he only visiting, like Win?

“What’s the big deal with ten seconds?” Brian continues. “Well, there should be zero difference. That’s the big deal. All neutrons are identical and their behavior shouldn’t change depending on where they are.”

Thane Bernard is not on Facebook or Twitter or Instagram or Snapchat. I can’t use a missing person’s website because he’s not technically missing. There are zero T. Bernards in the French white pages, but in today’s world of cellphones that means nothing. There is a Thane Bernard in academia, but he is on staff at USC and his field is ballet.

“There are two explanations,” Brian says. “Either neutrons are breaking down into something other than protons—although there’s no proof of this—or they somehow cross over into a mirror world and become mirror neutrons for ten seconds before flipping back. If that’s the case, maybe another world—even a multiverse—exists.”

I start typing Thane’s name into an international search engine for finding people. There is a fifty-dollar fee. I type in my credit card number.

“Before you go thinking that your physics professor needs a straitjacket, I offer this: we know—we have known since the 1970s—that dark matter in the universe outweighs visible matter by a ratio of six to one. But no one has ever been able to find it. There’s a world, literally, in which dark matter is hidden away. If that’s the case, the mirror world those neutrons are disappearing to briefly is huge. Huger than our own.”

Suddenly Brian’s phone dings. He looks down at it and frowns. “I think our credit card just got stolen,” he says. “I got a fraud alert from something called LocateTheLost.com.”

I fold down the clamshell hinge of my laptop. “Actually, that was me.”

“Who are you looking for?”

“I’m looking on behalf of someone who’s looking for someone. It’s one of my clients.”

“Your client is missing?”

“No. She wants to write a letter to someone she lost touch with years ago.”

“Like a secret love child?” For all of Brian’s braininess, he has a melodramatic streak. It’s why he insists on seeing Marvel Universe movies the day they come out, and why he conveniently manages to be in the room every time I’m watching The Bachelor.

“No,” I tell him. “It’s a man she used to love. She also wants me to deliver it to him.”

“Wait, what?” he says. “Is this Win? The one with ovarian cancer?”

I nod.

“You can’t do that,” he says.

In all the years I have been a death doula, I can count on one hand the number of times Brian has questioned my judgment. The biggest argument we had sprang from a client who wanted me to look into assisted suicide for her. I just didn’t feel right about it, and referred her to another death doula who does. Brian, however, was angry that I hadn’t tried to talk her out of it. She had a son who was a sophomore in high school, and Brian felt that it was irresponsible to not try to stop her.

“She’s the one who’s married to the driving instructor?” Brian clarifies, and I realize that all the time I’ve thought he was tuning out, he has actually been listening carefully.

“Felix. Yes.”

“And he’s okay with this?”

“He doesn’t know,” I admit. “He won’t find out.”

“Do you really believe that? What if the missing guy writes back?”

“There won’t be a return address.”

Brian shakes his head. “It’s still better to know than to be blindsided. What if, when Felix is putting away Win’s clothes and her books and whatever after she’s gone, he finds a note from this guy, or a ticket to a show he’s never seen, or a photograph of his wife looking happier than she ever looked with him?”

I think about the canvas in the locked room and say nothing.

“The guy is already dying by degrees. You’re going to kill him twice.”

“That’s not fair. Felix isn’t my client, Win is.” I gesture to his notes. “How do you know that in another universe, she isn’t living happily with this other man?”

“How do you know that she is?”

“I don’t really understand why, out of the blue, you’ve suddenly decided you’re an expert in my field,” I say coolly.

“Because you’re being a hypocrite.”

At that, I think of my dream of Wyatt, and my face is so hot I turn away.

“You’re helping a woman on her deathbed keep a secret. No, actually, it’s worse than that. You’re the match that could burn down that whole marriage even after she’s gone,” Brian says. “But you were angry at me for not telling you about every moment I spent with Gita where nothing happened.”

“I would have been angry even if you did tell me,” I explode. “The only difference is that if you’d told me, I would have known right away that there was apparently something so wrong between us that you had to go looking for it somewhere else!”

My voice rings in the silence between us. One thing I’ve always told caregivers and clients is that last words are lasting words.

I’ve always wondered what’s preferable: knowing the worst, or not knowing. Is it better to get a terminal diagnosis and count the days till you die, but have the time to say goodbye to everyone and everything you love? Or is it better to die immediately—an accident, a stroke, an aneurysm—and not have to wait for the inevitable? I think the answer is: neither. Both outcomes are terrible ones.

“There are things I’ve never asked you about…before we met,” Brian says haltingly, and suddenly the reason for his indignation is laid bare. “I figured, after all this time, you’d have told me everything.”

There are things you wouldn’t want to know, I think. But I look him in the eye. “I have,” I say, because what’s one more lie.

* * *

—

FOR THE PAST few days, I’ve relayed to Win that I’ve been searching for Thane Bernard. She has had more energy lately, which happens sometimes before the end.

She knows that I haven’t made any significant headway, but I think that the mere fact someone is looking for Thane makes her feel as if the world is righting itself. “Maybe we should write that letter,” I tell her, multiple times, but Win shushes me.

“We have to do something else first,” she insists, and then she asks me to run an errand.

I come home from the art supply store with everything on Win’s list. She is too weak to stretch a canvas herself, so she directs me with military precision. The way you know if you’re stretching a canvas right, Win tells me, is if there’s tension.

I seal and prime the canvas, and we let it dry, and then Win asks me to go to the locked room and retrieve her paints. She keeps them in a plastic tackle box. Some tubes are so crusted over that I have to wipe their necks with warm water to get the caps unscrewed. I prop up Win with pillows on a window seat where the light is good. I watch her squeeze thumbnail-size bits of color onto a glass palette: white, cadmium red, cadmium yellow, ultramarine. From the primary colors, she blends purple and green and orange. She shimmies an entire scale from red to blue, filling the middle with purple shadows. She gives rise to rainbows.

I check out the window to make sure that Felix’s car is still gone. “Do you know Thane’s birthday?” I ask. “That would help me.”

“Why?”

“Because when you use online search engines to find missing people, it’s the first thing they ask.”

“He isn’t missing.”

“Well, that’s the other problem. And he’s overseas. Almost every database I’ve found is American. Plus, I don’t speak French, so I have to use Google Translate for everything.”

“I know he’s a Leo, that’s all. But we didn’t talk about our ages.”

Why would they, when he was her professor? When it only highlighted the differences between them?

“I know he was nearly forty,” Win says. “Which at the time, felt ancient.”

It would, to a twenty-year-old. I remember Win telling me that his wife had been pregnant. I wonder how old she was.

“Tell me again where you’ve looked,” she asks, as she touches her brush to the canvas.

“Facebook. Twitter. Instagram,” I say. “Genealogy websites. The white pages. The prison system in France.”

“What?”