Ugetsu is set in villages which line the shore of Lake Biwa in Ōmi Province in the late 16th century. It revolves around two peasant couples – Genjurō and Miyagi, Tōbei and Ohama – who are uprooted as Shibata Katsuie's army sweeps through their farming village, Nakanogō. Genjurō, a potter, takes his wares to nearby Ōmizo. He is accompanied by Tōbei, who dreams of becoming a samurai. A respected sage tells Miyagi to warn her husband about seeking profit in time of upheaval, and to prepare for a probable attack on the village. Genjurō arrives with his profits, but she asks him to stop. Genjurō nevertheless works long hours to finish his pottery. That night Nakanogō is attacked by soldiers, and the four main characters hide out in the woods.
Father Michael Logan (Clift) is a devout Catholic priest in Ste. Marie's Church in Quebec City. He employs German immigrants Otto Keller (O. E. Hasse) and his wife Alma (Dolly Haas) as caretaker and housekeeper. Otto also works part-time as a gardener for a shady lawyer called Villette.
Sam Hurley (Stephen McNally) and Bart Moore (Paul Kelly) escape from prison, although Moore is seriously wounded in the breakout. They meet up with a confederate, a mute named "Dummy" (Frank de Kova), and hide out in a ghost town. Along the way, they pick up several hostages, Kay Garven (Alexis Smith) and her lover Arthur Ashton (Robert Paige), reporter Larry Fleming (Keith Andes), dancer "Dottie" Vale (Jan Sterling), and the town's sole resident, Asa Tremaine (Arthur Hunnicutt).
Homicide detective Sergeant Dave Bannion (Glenn Ford), is an honest cop who investigates the death of fellow officer Tom Duncan. It would seem to be an open-and-shut case, suicide brought on by ill health. Bannion is contacted by the late cop's mistress, Lucy Chapman (Dorothy Green), who claims it could not have been suicide. She says that the Duncans had a second home, which would not have been possible on his salary. Bannion visits Mrs. Duncan (Jeanette Nolan). He asks for particulars on the second home and she resents the implication. The next day, Bannion gets a dressing-down by Lieutenant Ted Wilks (Willis Bouchey), who is under pressure from "upstairs" to close the case.
Frenchmen Mario and Jo, Dutchman Bimba and Italian Luigi are stuck in the isolated Southern Mexican town of Las Piedras. Surrounded by desert, the town is linked to the outside world only by a small airport, but the airfare is beyond the means of the men. There is little opportunity for employment aside from the American corporation that dominates the town, Southern Oil Company (SOC), which operates the nearby oil fields and owns a walled compound within the town. SOC is suspected of unethical practices such as exploiting local workers and taking the law into its own hands, but the townspeople's dependence upon it is such that they suffer in silence.
Thérèse is unhappily married to her cousin, a haberdasher in poor health. They share their home with his domineering mother who makes Thérèse's life even more miserable. When she attempts to run away with a truck driver she has fallen in love with her husband tries to prevent her, forcing her lover to take extreme action.
Two men (Edmond O'Brien and Frank Lovejoy) from El Centro, California are driving toward a planned fishing trip at the Mexican town of San Felipe on the Gulf of California. Just south of Mexicali, they pick up a hitchhiker named Emmett Myers (William Talman), whose stolen car has apparently run out of gas. Myers turns out to be a psychopath who has committed multiple murders while hitch-hiking between Illinois and Southern California, and has managed to slip into Mexico at Mexicali. In order to evade the pursuing authorities, Myers forces the two men at gunpoint to journey deep into the heart of the Baja California Peninsula, toward the town of Santa Rosalía, where he plans to take a ferry across the Gulf of California.
After a fatal car crash in Lordsburg, New Mexico, investigators find a mysterious machine component that they turn over to the nearby Los Alamos National Laboratory for identification. Scientists there declare that it is one component of an advanced portable nuclear weapon designed by an unknown, presumably hostile power. The discovery prompts Paul Reagan (Richard Denning), chief of the Security Investigation Division (SID), to send agent John Williams (John Ireland) to investigate the source of these components and to prevent them from being assembled into a functioning weapon. As more parts are smuggled into the United States, the investigation expands and a pattern begins to emerge which points to Marseilles, France.
Whitney "Cam" Cameron (Joseph Cotten) arrives at a hospital to be with his widowed sister-in-law Lynne (Jean Peters), whose stepdaughter Polly has died under mysterious circumstances. A doctor cannot determine the cause of the child's death.
Tom Buchan (Colleano) is an alcoholic journalist whose once memorable work has been destroyed by his constant drunken antics that have cost him his future. Buchan boasts to his colleagues that they report news, whilst he makes it. He sees a chance for redemption by getting the life story of Gino Rossi (James), an Italian crime boss on the run. He wins Rossi's confidence by tipping him off to the police coming to arrest them (after Buchnan himself tipped off the police).
Hannah Haynes, a pretty girl who competes in a beauty contest, dreams of moving away from her New York slum neighborhood. So does older brother Chuck, who has a chance to land a new job on Long Island, but is hit by a car and needs to recover first.