The Butterfly Effect is a 2004 American science fiction thriller film written and directed by Eric Bress and J. Mackye Gruber, starring Ashton Kutcher and Amy Smart. The title refers to the butterfly effect, a popular hypothetical situation that illustrates how small initial differences may lead to large unforeseen consequences over time. It was shot in and around Vancouver, B.C., Canada, with prominent scenes shot at the University of British Columbia
College student Evan Treborn (Ashton Kutcher) is afflicted with headaches so painful that he frequently blacks out. While unconscious, Evan is able to travel back in time to difficult moments in his childhood. He can also alter the past for friends, like Kayleigh (Amy Smart), who was molested by her father (Eric Stoltz). But changing the past can drastically alter the present, and Evan finds himself in nightmarish alternate realities, including one where he's locked away in prison.
