Bruce wants to change the future, traveling back in time to make it so. Specifically, he intends to kill the man that killed his wife. Emily Blunt is the mother of the man that Bruce is after. Joseph Gordon is caught in the middle - maintain the status quo and carry out his plans for the future or team with Bruce.
Good movie... would hold as a safe first date movie but would see it later on in the relationship. Main reason is the story line does not fit a first date movie, else it still is a good movie.