During one of Oregon’s most violent storms, a young cellist seeks solitude and comfort in the safety of her large apartment, but soon realizes she might not be home alone.

Seo-jin is a widower still grieving his wife’s death. Then he receives the news that his long-lost younger sister, Yoo-jin, who went missing 25 years ago, has turned up. Unlike the rest of his family, who welcome her into their arms, Seo-jin feels that Yoo-jin is a stranger.

The overnight stock crew of a local supermarket find themselves being stalked and slashed by a mysterious maniac.