Homer, Barney and Moe join the Naval Reserve. During a routine drill, the would-be seamen find themselves trapped in a nuclear submarine in very real combat with another squadron. When Homer accidentally ejects Captain Tenille, the submarine's chief, he is put in charge of the vessel. The sub gets lost and coasts all the way to Russia. What's worse, it springs a leak and is rapidly filling up with water. Eventually, Homer saves his men and narrowly averts a nuclear conflict with the Russians. He is court-martialed, however, and forced to return to his normal life.