The realtor called the staircase a "feature." It dropped past our new cellar, past a wine room nobody asked for, all the way down to a cold concrete floor. In Hollow Marsh, every house had one, each deeper than the last, like the town was competing. Our first night, Mrs. Edevane from next door knocked. "Whatever you do," she said, "don't go past the frost line."

My little brother Theo didn't wait for warnings. By the time I turned around, he was already three steps down, giggling, counting each one out loud. "Seven, eight, nine," he sang. His voice echoed up wrong, like the stairs were much longer than they looked.

Theo wouldn't come back up. He sat on the cold step, head tilted, listening. "They're telling me a secret," he said, smiling at the wall. When I pulled him, his skin was freezing, and he kept whispering numbers I'd never taught him. Counting down instead of up.

I carried Theo back up, but he kept counting down. "Three. Two." At "one," every light in the house died. When they flickered back, Theo was smiling at me with too many teeth, and the real Theo was the one now crying somewhere far below the frost line. I had brought the wrong brother home.