Helen, a London ad executive, is fired from her job and rushes out to catch a train, but, as she runs down, her life suddenly splits off. In one version she catches the train; in the second, she misses it. Her whole life changes in that one second, and the rest of the film depicts what happens in each scenario.

Despite the gimmicky feel of the split narratives, the movie is watch-able due to the winning performances by the cast.