In Seattle, detective Quentin Conners is unfairly suspended and his partner Jason York leaves the police force after a tragic shooting on Pearl Street Bridge, when the hostage and the criminal die. During a bank heist with a hostage situation, Conners is assigned in charge of the operation with the rookie Shane Dekker as his partner. The thieves, lead by Lorenz, apparently do not steal a penny from the bank. While chasing the gangsters, the police team disclose that they planted a virus in the system, stealing one billion dollars from the different accounts, using the principle of the Chaos Theory. Further, they find that Lorenz is killing his accomplices.
Evan (Kutcher) mournes over his girlfriend's death while recolleting his childhood memories of his blackouts. But in the process discovers that he has the ability to go back in time and alter the past. But everytime he changes something, it goes wrong. Which, on a personal note, makes the tagline work well. "Change one thing. Change everything."