Martin Freeman stars as Chris, a frustrated TV producer who is worried about his unreliable flatmate Bob's habit of spending all day in the cellar creating his bizarre works of art.

Pining for his ex-girlfriend and fed up with his career as a producer of the late-night comedy show, Chris has decided to sell his flat in the vague hope of gaining control of his life. Forced to leave Bob in charge of showing a series of real estate agents around his house, Chris asks his friend to listen out for the door bell.

Meanwhile, a neurotic and fastidious American gangster named Mr Gaspardi (Corey Johnson) is being chauffeured to the airport by his vain, celebrity-obsessed British host, a London criminal named Dennis Earle (Danny Dyer), when he is struck down by chronic food poisoning.

Running out of petrol, the incapacitated yet toilet-phobic American is forced to use the lavatory of the nearest house; Chris' house. Mistaking them for estate agents, Bob invites them in. When the sick gangster emerges from the lavatory he finds that his trigger-happy partner has shot a hole in a water main and set in motion an accidental hostage situation that soon involves an ever-growing list of bizarre captives.