In The Butterfly Effect Evan Treborn (Ashton Kutcher) has lost crucial moments of his life, his childhood scarred by a series of terrifying events he can't remember. When Evan realises that by reading his diaries he can unlock the past and go back in time, he tries to reclaim the missing memories by tampering with the past... with unexpected and distastrous results! The more Evan tampers with time, the more his life, and those of his friend Kayleigh (Amy Smart) begin to unravel, and he discovers there is no such thing as a happy ending!
this is a complete B movie that just manages to be watchable, lots of different bits of plot are crammed in and some of the script is just laughable. however i did keep watching to the end somehow but was amazed how this film got 9/10.