On a remote island, a tragic incident occurs in 1946 when a young woman named Ida Parsons is brutally assaulted by a man at a secluded party. After fighting back and killing her attacker, she becomes reclusive, retreating to the family-owned island to live in solitude. Decades later, a group of young adults on a boating trip, including siblings Sandy and Eric, find themselves stranded on the same island due to engine trouble and an accidental fire that destroys their boat.

As they explore the island in search of help, they stumble upon an abandoned mansion and realize someone dangerous might be living there. They begin to uncover the dark history of the island and its reclusive inhabitant. Tensions rise and fear mounts as they encounter signs of a monstrous presence stalking them. With no means of escape, the group must rely on their wits and resourcefulness to survive the unknown terror that lurks, waiting to strike.