The Lambda Lambda Lambdas from Adams College head to a national fraternity convention in Fort Lauderdale, Florida. Lewis’ best friend Gilbert cannot come, due to breaking his leg during a chess game. At the Royal Flamingo Hotel, a trainee named Sunny informs Lewis that their reservation is canceled and has been given to the Alpha Betas. The acting manager Buzz explains to Sunny that they do not want nerds staying in the hotel. The Tri-Lambs also meet Sunny’s friend Stewart, a geeky bellboy. Poindexter finds a dilapidated hotel called the Hotel Coral Essex, located in a shady neighborhood, and makes their reservation there. Roger Latimer, the president of the local chapter of Alpha Betas (and chairman of the regional conference), along with Ogre and his fellow Alphas plan to get rid of the Tri-Lambs.
Heading to the United Fraternity pre-conference barbecue, the Lambdas end up in the Florida swamplands (intentionally given wrong directions by Roger) and confront a group of Seminole Indians in an ancient Mayan temple, an act concocted by the Alphas to humiliate the Tri-Lambs into leaving the conference. They are captured, forced to strip to their underwear, chased by alligators and later Ogre, and forced to make their way across town back to their hotel in their underwear.
The next day, Roger announces a new bylaw to be voted upon by the conference: “Proposition 15”, which would require physical as well as academic standards to be met by all members of the conference. Lewis’s argument against the proposition is co-opted by a wet-nightie contest happening poolside. The Lambdas decide to beat the Alphas at their own game and throw a party at the Hotel Coral Essex. The neon sign outside the hotel is deliberately broken so that it reads “Hot oral sex”, which draws people for miles. The Tri-Lambs perform a rock/rap “No On 15” song outside of the hotel, winning over the crowd. Prop 15 is voted down the next morning. Roger expresses a desire to make peace with the Tri-Lambs, and to that end he proposes a bylaw stating that any fraternity found guilty of a crime will be expelled from the conference and their charter revoked. The Lambdas, satisfied that the Alphas now cannot attack them without being expelled from the conference, accept their offer of friendship and their luxurious hotel suite at the Royal Flamingo. Roger encourages Sunny to grab a couple of girls and take the Tri-Lambs to the beach in his car. On the beach Sunny and Lewis get to know and like each other. Roger reports his car stolen, and the Lambdas are arrested.
Stewart and Sunny bail the Tri-Lambs out of jail. Sunny apologizes and explains that she knew nothing of Roger’s plan, but Lewis does not believe her. The Alpha Betas kidnap the Tri-Lambs along with Sunny and dump them on an uninhabited island. Disgusted by Roger’s actions, Sunny jumps overboard. When they realize Ogre cannot be trusted to keep his mouth shut, they also throw him into the water, despite the fact that he cannot swim. Wormser jumps into the ocean and rescues Ogre. After smoking some marijuana Booger discovered on the island, Ogre and the others realize he is not so different from them after all. As the group sleeps Lewis has a dream about Gilbert, who implores Lewis not to give up and points out that Lewis is acting like a jerk to Sunny, who is stranded with him by choice. This helps give Lewis the confidence he needs to apologize to Sunny and try to find a way off the island.
The next morning The Tri-Lambs find a Cuban military officer’s hidden cache of military supplies, including an amphibious boat/truck. At the conference, Roger is presiding over the vote to expel the Tri-Lambs, when, decked out in military gear, they crash the conference, driving right through the conference room wall, then chase the attendees out to the pool. Sunny reveals that Roger set them up and kidnapped them. Lewis punches Roger in the jaw, knocking him into the pool. The fraternity council vote Roger and the Alphas out of the fraternity council and revoke their charter.
Back at Adams College, Lewis and Gilbert lead an induction ceremony for the newest member of Lambda Lambda Lambda, Ogre.