So I follow Katie downstairs, watching the shifts in her musculature beneath the gown, the way her legs move, the tightness of her hips.

When the lights go on, I see the room where Paul and I worked so many nights. The place is unchanged, untouched by preparations for the ball, a geography of notes and drawings and books piled into mountain ranges that thread through the room, as tall in places as we are.

It's not as hot in here, I say, searching for something to tell her. They seem to have turned down the thermostat in the rest of the building to keep the first floor from overheating.

Katie looks around. Paul's notes are taped to the shoulders of the fireplace; his diagrams feather the walls. We are surrounded by Colonna.

Maybe we shouldn't be in here, she says.

I can't tell if she's worried that we'll intrude on something of Paul's, or that Paul will intrude on something of ours. The longer we stand, sizing up the room, the more I can feel a distance forming between us. This is not the place for what we need.

Have you ever heard of Schrodinger's cat? I say finally, because it's the only way I can think to raise what I'm feeling.

In philosophy? she says.

Anywhere.

In my lone physics class, the professor used Schrodinger's cat as an example in wave mechanics, when most of us were too slow for v = -e2/r. An imaginary cat is placed in a locked box with a dose of cyanide, which will be given only if a Geiger counter is triggered. The catch, I think, is that it's impossible to say whether the cat is living or dead before you actually open the box; until then, probability requires you to say that the box contains equal parts living and dead cat.

Yes, she says. What about it?

I feel like the cat isn't dead or alive right now, I tell her. It's nothing.

Katie puzzles over what I'm getting at. You want to open the box, she says at last, sitting on the table.

I nod, propping myself up beside her. The enormous wooden plank accepts us silently. I don't know how to tell her the rest of what I mean: that we, individually, are the scientist on the outside; that we, together, are the cat.

Instead of answering, she takes a finger and runs it behind my right temple, tucking my hair behind my ear as if I've said something charming. Maybe she already knows how to solve my riddle. We are bigger than Schrodinger's box, she's saying. Like any good cat, we have nine lives.

Does it ever snow like this in Ohio? she says, consciously changing the subject. Outside, I know, it's begun again, driving down with more power than before, all our winter in this one storm.

Not in April, I say.

We're side by side on the table, just inches apart. Not in New Hampshire either, she says. Not in April, at least.

I accept what she's trying to do, where she's trying to take me. Anywhere but here. I've always wanted to know more about what her life was like at home, what her family did around the dinner table. Upper New England in my imagination is the American Alps, mountains at every turn, Saint Bernards bearing gifts.

My little sister and I used to do this thing in the snow, she says.

Mary?

She nods. Every year when the pond near our house would freeze over, we would go crack holes in the ice.

Why?

She smiles, beautiful. So the fish could breathe.

Members pass across the top of the stairs, little pockets of heat in motion.

We would take the ends of broomsticks, she says, and make holes all the way across the lake. Like punching holes in the top of a jar.

For fireflies, I say.

She nods and takes my hand. The ice skaters used to hate us.

My sisters used to take me sledding, I tell her.

Katie's eyes twinkle. She remembers she's got something on me: that she's a big sister, and I'm a little brother.

There aren't a lot of big hills in Columbus, I continue, so it was always this one.

And they would drag you up the hill on the sled.

Did I tell you this already?

That's just what big sisters do.

I can't imagine her pulling a sled up a hill. My sisters were strong as pack dogs.

Did I ever tell you about Dick Mayfield? I ask her.

Who?

This guy my sister used to date.

What about him?

Sarah used to kick me off the phone every time Dick would call.

She hears the jab in it. This, too, is what big sisters do.

I don't think Dick Mayfield had my number. She smiles, folding her fingers into mine.

I can't help thinking of Paul, of the dovetail he made with his hands.

Dick had my sister's number, I say. All it took was an old red Camaro with flames traced on the sides.

Katie shakes her head disapprovingly.

Study Dick and the Chick Machine, I tell her. I said that one night when he came over, and my mother made me go to bed without dinner.

Dick Mayfield, conjured from thin air. He called me Tiny Tom. We went riding in the Camaro once, and he told me a secret. It doesn't matter how small you are. All that matters is the size of the fire in your engine.

Mary dated a guy who drove a '64 Mustang, Katie says. I asked her if they were doing anything in the backseat. She said he was too uptight about messing up the car.

Sex stories sublimated into car stories, a way to talk about everything without talking about anything at all.

My first girlfriend drove a water-damaged VW, I tell her. You would lie down on the backseat, and this smell would come up, like sushi. You couldn't do anything back there.

She turns to me. Your first girlfriend could drive?

I fumble, realizing what I've given away.

I was nine, I say, clearing my throat. She was seventeen.

Katie laughs, and a silence follows. Finally, the moment seems to have come.

I told Paul, I say to her.

She looks up.

I'm not working on the book anymore.

For a while she doesn't respond. Her hands rise to her shoulders, rubbing them for warmth. I realize, after so many hints, so much contact, that she hasn't gotten over the temperature of the room.

Do you want my jacket? I ask.

She nods. I'm getting goose bumps.

It's impossible not to look. Her arms are covered with tiny beads. The curves of her breasts are pale, the skin of a porcelain dancer.

Here, I say, taking off the jacket and placing it across her back.

My right arm passes her far shoulder just for a second, but she reaches up, holding it in limbo. With me half crooked around her, waiting, she leans in. The smell of her perfume returns, carried in the bell of her hair. This, at last, is her answer,

Katie cocks her head, and I reach inside the jacket, into the dark space where it hangs off her shoulders, placing a hand on the far side of her waist. My fingers stick to the rough fabric of her gown, caught by an unexpected friction, and I find that my hold on her is tight and effortless at the same time. A strand of hair falls in front of her face, but she doesn't brush it back. There is a smudge of lipstick just below her lip, so small that it can only be seen from a tiny distance I'm surprised to find I have reached. Then she is too close to focus on anything at all, and there is warmth over my mouth, lips closing in.