The story opens in the wintry wasteland of the year 2035, where a virulent plague has forced humans to live in a squalid, oppressively regimented underground. Bruce Willis plays a societal outcast who is given the opportunity to erase his criminal record by "volunteering" to time-travel into the past to obtain a pure sample of the deadly virus that will help future scientists to develop a cure. But in bouncing from 1918 to the early and mid-1990s, he undergoes an ordeal that forces him to question his own perceptions of reality. Caught between the dangers of the past and the devastation of the future, he encounters a psychiatrist (Madeleine Stowe) who is initially convinced he's insane, and a wacky mental patient (Brad Pitt) with links to a radical group that may have unleashed the deadly virus.