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.
High School grad and all American gal, Anna, finds her purpose and herself after she hooks up with the radical feminists in The Itty Bitty Titty Committee.
Everyone has 'moved on', except for Sherman and Jim Levenstein's still understanding father. Little Matt Stiffler wants to join his older brother Steve's business and, after everything Matt has heard from Jim's band-geek wife, he plans to go back to band camp and make a video of his own.
