Bart Hughes is a successful New York businessman living in a renovated brownstone with his wife Meg and their young son. As his family leaves for a vacation, he stays behind to work on a crucial project that could significantly boost his career. The tranquility of his solitude is shattered when he discovers signs of a rodent infestation within the walls of his home. Initially dismissive, Bart's irritation turns into obsession as the presence of an unusually intelligent and elusive rat challenges his sanity and safety.

Determined to exterminate the pest, Bart's initial attempts with conventional traps and poisons fail, pushing him to the edge of reason. His obsession with the creature grows, consuming his life and jeopardizing his job. As the battle between man and beast escalates, Bart’s meticulously structured world begins to crumble. Consumed by the need to defeat the rat, he resorts to increasingly extreme measures, turning his once-beautiful home into a battleground. This conflict becomes a deeply personal battle of wits and survival, testing the limits of his sanity and physical endurance.