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."

Dad laughed off the warning and called Hollow Marsh "charmingly weird." That night I heard tapping under the floor. Slow, patient knocks, coming up through the concrete from somewhere far below the cold floor we'd already seen. Tap. Tap-tap. Like something asking to be let in.

I followed the tapping down to the concrete floor with a flashlight. The sound came from a thin crack in the middle, wide as a finger. I knelt and shined the light in. An eye, huge and wet, was pressed against the crack, looking right back up at me. Then it blinked.

I jammed concrete patch into the crack and sealed the eye away. For a week it was quiet. Then I noticed the crack had reopened somewhere new, in my bedroom floor, right under my pillow. It had simply come up to a higher floor to be closer to me. The patient eye was back, and it had missed me.