Peter starts an anti-immigration group after being caught up in the pro-American sentiment at a Veterans' Day parade, but his tune quickly changes when he finds out he was born in Mexico. Unable to prove his citizenship, pass the naturalization test or convince investigators that his marriage to Lois is for real, he ends up working as a groundskeeper on his father-in-law's estate and leading the fight for immigrant rights .

Peter decides to grow a moustache, but then he's mistaken for a fireman, so he lends a hand when a fire breaks out at a local fast food restaurant. The owner gives him unlimited burgers as a "thank you" but he eats so many that he eventually has a stroke. When Peter recovers, he vows to expose the fast-food company and becomes friends with a genetically engineered cow he meets after infiltrating the McBurgertown warehouse.