I wave to Ronald, the doorman, and take the elevator up to my apartment. I change out of my blazer, blouse, and slacks, putting on a one-piece swimsuit instead. Then I grab my waterproof headphones and head up to the pool.

The pool is on the roof of our building.

In the summer, they open up the atrium overhead, so you can swim under the stars. In the winter, it’s enclosed from the elements, though you can still see the sky through the glass.

I love to lay on my back and swim back and forth, looking up.

I’m usually the only person in the pool when I come this late. Sure enough, tonight the space is dim and quiet, the only noise the water lapping against the rim of the pool.

It smells of chlorine, and fabric softener from the fresh stacks of towels laid out on the lounge chairs. After turning on my swimming playlist, I set my phone down on one of the chairs.

I’m about to jump in the pool when I realize I forgot to fix my hair. I usually braid it and put it under a swim cap, so the chlorine doesn’t dry it out. Red hair is fragile.

It’s still in a chignon from work, twisted up with one of those two-pronged hairpins.

I don’t really want to go all the way back down to my apartment. This will be fine, for one single time.

I put my hands over my head and dive into the water with one, clean jump. I stroke back and forth across the pool, listening to “California Dreamin’ ” on my headphones.

California Dreamin’—The Mamas and the Papas (Spotify)

California Dreamin’—The Mamas and the Papas (Apple)

I’m wearing goggles, so I can look down into the bright blue water, illuminated with pot lights from below. I see a dark shape down in the corner of the pool, and I wonder if somebody dropped something down there—a gym bag or maybe a canvas bag of towels.

Turning over, I lay on my back and look up at the glass ceiling. It reminds me of a Victorian greenhouse—the glass bisected by a latticework of metal. Beyond the glass I see the black sky, and the pale, shimmering disc of a nearly-full moon.

As I’m looking up, something locks around my throat and drags me down under the water.

It pulls me down, down, all the way down to the bottom of the pool, heavy as an anchor.

The shock of something grabbing me from below made me let out a shriek, and now there’s almost no air in my lungs. I kick and struggle against this thing that’s caught hold of me. I claw at the thing wrapped around my throat, feeling spongy “skin” with hard flesh beneath.

My lungs are screaming for air. They feel flat and deflated, the pressure of the pool pressing against my eardrums and my chest. I twist around just a little and see black flippers kicking by my feet, and two arms in a wetsuit wrapped tightly around me.