Luna arrives at 44 Poplar Street in Millbrook, Vermont, on a cold October evening in 2018, house-sitting for a friend of a friend. The key is under the mat, just as promised. Inside, the house is clean and unremarkable, but there's a photograph on the fridge: a woman who looks exactly like Luna, wearing a dress she doesn't own, standing with a man she doesn't know. The date on the photo is five years from now. Luna tries to leave, but the front door won't open from the inside. She waits out the week in the living room, watching the woman in the photographs move closer to the camera each day. A story about doubles, locked doors, and the version of yourself you never met.