When Sarah Marshall dumps aspiring musician Peter Bretter for rock star Aldous Snow, Peter's world comes crashing down. His best friend suggests that Peter should get away from everything and to fly off to Hawaii to escape all his problems. After arriving in Hawaii and meeting the beautiful Rachel Jansen, Peter is shocked to see not only Aldous Snow in Hawaii, but also Sarah Marshall.
Devastated Peter takes a Hawaiian vacation in order to deal with the recent break-up with his TV star girlfriend, Sarah. Little does he know, Sarah's traveling to the same resort as her ex - and she's bringing along her new boyfriend.