Have you ever done something in a relationship so horrible, so stupid, that you wish you could go back and fix it? Victor (Douglass Henshall) did. He cheated on Sylvia (Lena Headey) and then told her about it. As a result, they broke up, and now that she is getting ready to marry another many, Victor realizes what a buffoon he was, and wishes things happened differently. Here is where Twice Upon A Yesterday is different from most other romantic movies. Victor does get a second chance.

While wallowing in his sorrow, he meets two garbage men that may or may not be the reincarnations of Don Quixote and Sancho Panza. It sounds very strange, but seems perfectly normal when you're watching this movie. After some revelry, he falls asleep, and wakes up in the morning, wanting to go home. On his way home, he begins to realize that something is wrong. No, not necessarily wrong. Somehow, he has gone back to the day when he told his girlfriend. This is his second chance. He resolves not to tell her, and to become a great boyfriend. After all, she is the right woman for him. Sylvia notices the change in, and she likes it. Then, again, things start to move out of Victor's control. She meets the man that previously (or depending on how you look at it, in the future) she was to marry. No one realizes this except Victor, and he does everything he can to try and quell their obvious attraction to each other. Then, he meets an attractive bar tender (Penelope Cruz), and things get even more complicated.