I touched the frost line with one finger and the cold ran up my arm like a shock. Below me, in the dark, dozens of voices sighed at once, happy I'd finally reached them. A hand made of frost closed gently around my ankle and pulled. I grabbed the rail and screamed for Dad.

Right at the frost line, I found a small door I hadn't seen before, set into the stone wall. A brass plate read OWNER. I opened it. Inside was a list of every family that had ever lived in our house, each name crossed out. The last name on the list was mine, not crossed out. Yet.

I refused to cross the frost line and backed up the stairs slowly, never turning my back. The cold followed me, step by step, like a slow tide. By the time I reached the top, frost had spread across the whole staircase wall, and my warm hand left no print on it at all. I shut the door and stuffed towels under it. The house stayed ours, mostly. But it gets colder every winter, and the frost line climbs one more step each year.