After being fired for causing a near meltdown, Homer joins the Naval Reserve. Meanwhile, Bart gets an earring after seeing how it transforms Milhouse from being a nerd to being cool. Homer disapproves. After graduating from basic training, Homer goes off on a mission of war games; before he leaves, he chides Bart about the earring, and Bart gives it to him.

Assigned to a navy sub, Homer makes fast friends with the captain, who leaves him in charge when he goes to check on a blocked torpedo tube. When Homer believes the ship is being attacked, he orders the torpedoes fired, accidentally ejecting the captain.

Homer gets the sub lost, so that it is directly en route to Russia. The media labels Homer a traitor. When the sub is bombarded by depth charges from the United States Navy, it springs a pinhole leak. Things look dire until Homer realizes he can use Bart’s earring to fix it. He has the sub surface and is taken into custody by the navy. Court-martialed, Homer beats the rap when the navy judges all must resign from the case due to various scandals in which they’re involved.