Stanley Webber lives in a seedy boarding house in an English seaside town, run by the elderly and daft Meg Bowles. His life is uneventful and unremarkable until one morning, Meg tells him that two strangers are coming to stay. These men, Goldberg and McCann, arrive under the guise of renting a room but soon reveal a menacing interest in Stanley. As Stanley's paranoia and fear escalate, Goldberg and McCann subject him to psychological torment, peppered with bizarre questions and obscure accusations.

The tension culminates as Meg prepares a birthday party for Stanley, even though he insists it is not his birthday. The celebration quickly devolves into chaos, revealing the cracks in everyone's facades. Throughout the party, bizarre and unsettling events unfold, pushing Stanley to his breaking point. The interactions between the characters become increasingly surreal and nightmarish, creating a pervasive sense of dread and uncertainty that builds to an ambiguous and unsettling conclusion.