The Prisoner of Benda.Farnsworth switches his body with Amy's using his latest invention so that he can relive his youth and Amy may gorge out like she always wanted. Upon doing so, they find they cannot switch their bodies back with each other, so they try to see if they can return to normal by switching their minds with the rest of the crew. Bender volunteers to switch minds with Farnsworth so he can use Amy's body to rob the yacht of Robohungarian emperor Nikolai, while Farnsworth joins a circus in Bender's body. Bender is caught by Nikolai, but tricks him into switching bodies with a robot bucket so he can live the life of an emperor. However, he discovers that Nikolai's wife and cousin are plotting to kill him, but is rescued by Farnsworth. Meanwhile, Leela switches bodies with Amy in Farnsworth's body when she comes to believe that Fry only loves her for her body, which leads to Fry switching bodies with Zoidberg to get back at her. To prove neither of them are shallow, the two go on a date and try to gross each other out until they ultimately make out and have sex. Amy, who switched bodies with Hermes after overeating in Leela's body so he may slim it back down, witnesses them making out and loses her appetite for good. In the end, everyone returns to their original bodies by adding the bodies of two Globetrotters who deduced the solution to the equation.