When Aldous realizes Sarah is clearly putting on a performance to provoke a reaction from Peter, he stops the sex and tells her the trip was a mistake as she's clearly not over Peter.
Devastated, and unable to banish his grief through one-night stands, Peter takes a trip to Hawaii.
Trouble ensues when he runs into his ex on the island as she is vacationing with her new boyfriend.
Composer Peter Bretter (Jason Segel) is in a five-year relationship with actress Sarah Marshall (Kristen Bell), who stars in a CSI-like television show titled Crime Scene: Scene of the Crime.
After a five-year relationship, Sarah abruptly breaks up with Peter.
Devastated by this event, he chooses to go on a vacation in Hawaii, in order to try to move forward with his life.