This movie follows the story of a young couple who become caught in a terrifying scenario when a dirty bomb explodes in their home city of Los Angeles. The day starts when Lexi (Mary McCormack) leaves the house to go to work leaving Brad (Rory Cochrane) at home. Soon after a series of explosions are heard. Brad tries several times to call Lexi but all of the phone lines are jammed. He leaves home to search for his wife but is forced to return home by the police. As the smoke from the explosion engulfs the city and drifts towards the suburbs it soon becomes clear that the fallout is toxic. Unable to contact his wife and frantic about her safety, his problems are made worse when martial law is declared and he is forced to seal up his home. Nightmare turns into reality when after sealing his home from the toxic air his wife arrives home unable to get into the house.