I wonder if Marie ever went out at night. Every once in a while. I wonder if Pierre ever pried a beaker full of uranium ore out of her hand and dragged her to Montmartre for a walk or a show. I wonder if they had fun, in the few years they had together.

Yes. I’m sure they did. I’m sure they had a blast. And I’m sure, like I’ve never been sure before, that she never regretted anything. That she treasured every second.

The solar lights are on in Levi’s yard, just bright enough for me to see the hummingbird mint, purple and yellow and red. I smile and lift the large, light box from the passenger seat, stopping to coo at it. I know about the spare key hidden under a pot of rosemary, but I ring the doorbell anyway. While I wait, I try to spy into the air holes I carved on the top. Can’t see much.

“Bee?”

I look up. Breathless. Not scared. I’m not scared anymore.

“Hi. I . . . Hi.” He’s so handsome. Stupidly, unjustly handsome. I want to look at his stupidly, unjustly handsome face for . . . for as long as I possibly can. Could be a minute.

Hopefully, it’ll be seventy years.

“Are you okay?”

I take a deep breath. Schrödinger’s here, too; staring up quizzically at me and my cargo. “Hi.”

“Hi. Are you . . . ?” Levi reaches for me. Abruptly stops himself. “Hey.”

“I was wondering . . .” I lift up the box. Hold it out to him. Clear my throat.

“I was wondering . . . do you think poor Schrödinger would hate us if we adopted another cat?”

Levi blinks at me, confused. “What do you—?”

Inside the box, Félicette explodes in a long, plaintive meow. Her pink nose peeks out from one of the air holes, her paw from another. I let out a wet, bubbly, happy laugh. Turns out I’m crying again.

Through the tears, I see understanding on Levi’s face. Then pure, overwhelming, knee-shaking joy in his eyes. But it’s only a moment. By the time he reaches over to take the box from my hands, he is grounded. Solid.

Profoundly, quietly happy.

“I think,” he says slowly, carefully, his voice a little thick, “that we won’t know until we try.”

EPILOGUE

HERE’S MY FAVORITE piece of trivia in the whole world: Dr. Marie Skłodowska-Curie and Dr. Bee Königswasser-Ward showed up to their wedding ceremonies wearing their lab gowns.

Well. Clothes. Gowns aren’t really a thing anymore. Unless you’re walking the red carpet at the Met Gala or . . . well, getting married, I guess.

Which I was. But. I was wearing a Target dress—yup, the Target dress—

which I sometimes wear at work. And I work in a NASA lab, which technically makes it “lab clothes.” I guess I’m a pragmatic gal, too.

Levi and I aren’t going to have a ceremony until this summer. July 26, to be precise. I’d explain why I picked that date, but it might shift your opinion of me from “quirky Marie Curie fangirl” to “dangerously obsessive stalker,”

so . . . yeah. I’ll let you google it, if you must. Anyway, even though we’re married, only a handful of people know. Reike, for instance (“Should I hyphenate my name, too? Mareike Königswasser-Ward. Nice ring to it, huh?”). Penny and Lily (our impromptu witnesses). Schrödinger and Félicette, of course, but they didn’t care too much when we told them. They just blinked sleepily at us and went back to napping on top of each other, stirring only when a dollop of celebratory whipped cream appeared.

Ungrateful creatures. I love them.

It’s a bit odd, the way our elopement came about. I noticed Levi’s frustration when, around the ninth time he proposed, I told him that I did want to marry him, but I was traumatized by the last-minute split of my previous engagement (and by the thousands of dollars wasted in security deposits). But the solution to this mess appeared to me in a dream. (That’s a lie: I was plucking my eyebrows.)

I secretly applied for a marriage license. Then, on a random Thursday morning, I told him I wanted to drive the truck (he was not a fan, but hid it well). He thought we were heading to work (hence the Target dress), but instead I sneakily navigated us to the courthouse. In the alreadycrowded early-morning parking lot, while he looked around to figure out where the hell we were, I told him I’d marry him that very day. That I couldn’t be afraid of him leaving me at the altar if we’d already tied the knot. That I wouldn’t even make him sign a prenup to prevent him from claiming rights to my limited-edition Empire Strikes Back DVD, because I wasn’t planning on divorcing him. Ever.

“I guess I should properly ask,” I said after methodically explaining my reasoning, “will you marry me, Levi?” To which he said, “Yeah.” Hoarse.

Tongue-tied. Breathless. Handsome, so handsome that I had to kiss him, a little tearfully. And by “a little” I mean “a lot.” And by “tearfully” I mean that snot was involved. It was ugly, kids.

And it was beautiful.

After a ninety-four-second ceremony we drove to the Space Center, made up an excuse for being late, and I had Lean Cuisine at my desk while frowning at the terrible signal dropout in the astronauts’ MRI scans. I only saw Levi once, in public, and the one interaction we were able to sneak was his hand briefly brushing my lower back. Yikes, right?

It was the best day of my life.

Unlike today. Today’s going to be the worst day of my life. It’s 8:43 a.m., and I already know it.

“Are you actually going to do this?” Reike asks, staring at the

“#FAIRGRADUATEADMISSIONS RACE, START LINE” banner above our heads.

“My heart says no.”

“And your body?”

“My body also says no. But louder.”

She nods, unsurprised. “You can probably do it. The 5K, I mean. For the love of the goddess, do not attempt the half marathon.”

“That’s a lot of trust from someone who has my same wimpy constitution and should know better.”

“It has nothing to do with constitution and everything to do with Levi training you for . . . it’s been what, eight months?”

“Eight months too long.”

We exchange a glance, laughing at each other. I love having Reike here.

I love that she and Levi arranged her visit behind my back and surprised me with it. I love her nagging us because we have only vegan food in the house and she’s “sick of competing with the cats for a meager slice of chicken breast!” I love that she’s hooking up with nose-tongue dude while she’s here. I love her. I love all of this.

“Are you going to do the race?” I ask.

“Yeah. It’s for a good cause. Not that I fully understand what a Ph.D. is, what graduate admissions are, or even why someone would voluntarily go to school, but if you say you’re helping traditionally underrepresented groups, I’m on board. Rocío and I will walk and chat. She’s planning to talk to me about yet-uncaught serial killers.”

“Lovely.”

“Isn’t she? I cannot believe you let her move back to Baltimore.”

“I know, but she got into her dream school, has an apartment with her dream girlfriend, and I’m pretty sure she’s a leader in the local Wiccan community. I’m just glad she and Kaylee managed to be here for the 5K after putting