In late 1945, one-armed John J. Macreedy (Spencer Tracy) gets off a train at the isolated desert hamlet of Black Rock. It is the first time in four years that the train has stopped there. After Macreedy states he is looking for a man named Komoko, several of the townspeople become inexplicably hostile. The hotel desk clerk, Pete Wirth (John Ericson), claims he has no vacant rooms. Hector David (Lee Marvin) threatens him. Later, Reno Smith (Robert Ryan) informs Macreedy that Komoko, a Japanese-American, was interned during World War II.
Certain that something is wrong, Macreedy sees the local sheriff, Tim Horn (Dean Jagger), but the alcoholic lawman is no help. The veterinarian and undertaker, Doc Velie (Walter Brennan), advises Macreedy to leave town immediately, but lets slip that Komoko is dead. Pete's sister, Liz (Anne Francis), rents Macreedy a Jeep. He drives to nearby Adobe Flat, where he finds a homestead burned to the ground, as well as wildflowers. On the way back, Coley Trimble (Ernest Borgnine) tries to run Macreedy off the road.