In the eerie atmosphere of a large, isolated house, twin sisters Lydia and Ellie Haskell navigate the complexities of their intertwined lives. Lydia, the more rational of the two, is increasingly aware of the dark shadows that loom over their existence, particularly as Ellie’s mental state deteriorates. The sisters have lived together for years, their bond deepened by shared memories and a haunting sense of isolation. However, the balance of their relationship begins to shift when Lydia makes a chilling decision: she purchases a coffin for herself. This act serves as a stark reminder of their mortality and the unsettling reality that one of them may not be entirely sane.