The American Pie gang is back together and ready to stir up more trouble than before. Following a year apart, the guys, Kevin (Thomas Ian Nicholas), Jim (Jason Biggs), Oz (Chris Klein), Stifler (Seann Williams Scott), and Finch (Eddie Kaye Thomas) come back together to compare notes after their first year in college. After renting a beach house in Grand Harbor to spend their summer, the guys set out on a quest to host their biggest party ever at the end of the summer.
Deciding that they should get summer jobs, the guys are hired to paint the house of two women. Normally responsible for finding the gang's shenanigans, Stifler mistakes the homeowners for lesbians. Jim, Stifler and Finch later find themselves in a highly awkward situation in hopes to being able to watch some risqué behavior courtesy of the homeowners.
Nadia (Shannon Elizabeth), Jim's lust interest from the previous American Pie film informs Jim that she will be coming to visit Jim at the end of the summer. Determined not to make a fool of himself yet again, Jim, enlists the assistance of his former prom date, Michelle (Alyson Hannigan), to help him "prepare" for Nadia's big arrival. Jim must endure his normal dose of embarrassment with his dad (Eugene Levy), as Jim finds himself in the Emergency Room after mistaking a tube of super glue for lube. Once Jim is all healed from his super glue escapade and Nadia arrives, Jim realizes that perhaps Nadia is not the girl for him and follows Nadia's advise to "Go, get your band geek...".
Oz and Heather (Mena Suvari) get creative to maintain their relationship from afar, as Heather is studying abroad in Spain. Heather returns for the big party.
Vicky (Tara Reid) returns for the big party, only to leave Kevin disappointed, as he is introduced to her new boyfriend.
Nadia, recently rejected by Jim, finds herself swooned by Sherman's (Chris Owen) Sherminator routine, as the two end up in bed together.
Finch, still pining after Stifler's mom (Jennifer Coolidge) has become involved in Tantra, claiming that he has learned how to "make an orgasm last for days". After spending the summer, disappointed that Stifler's mom hasn't returned, the morning after the party, a mysterious Mercedes arrives, the windows roll down, only to reveal that Stifler's mom is back. Finch hops in the car and the two drive off together.
The movie is stocked full of awkward, yet hilarious twist and turns, leaving viewers doubled-over in laughter and asking what is next for this feisty gang.