With high school a distant memory, Jim and Michelle are getting married — and in a hurry, since Jim's grandmother is sick and wants to see him walk down the aisle — prompting Stifler to throw the ultimate bachelor party. And Jim's dad is reliable as ever, doling out advice no one wants to hear.

In a futuristic New York known as New Rome, visionary architect Cesar Catilina dreams of building "Megalopolis," a utopian city that redefines society’s limits. Opposing him is the corrupt Mayor Franklyn Cicero, who clings to power and profit. Between them stands Julia, the mayor’s daughter, whose love for Cesar forces her to choose between loyalty, ambition, and the fate of humanity.