Fritz Lang directed this story of a traveler suspected of kidnapping who is lynched, only to escape while 22 lynchers are prosecuted for murder.
Joe Wilson (Spencer Tracy) and Katherine Grant (Sylvia Sidney) plan to marry but cannot afford it. So she takes a job in another town and gives Joe a ring he calls a "mementum." Joe objects to his brother Charlie (Frank Albertson) working for a gangster. Joe writes Katherine he is coming in his car; but he is stopped and arrested for kidnapping by deputy Bugs Meyers (Walter Brennan). Sheriff Tad Hummel (Edward Ellis) questions Wilson, and they find suspicious peanuts and a $5 bill that was in the ransom.
At the barbershop men talk about how people usually resist evil impulses; the rumor of an arrested kidnapper spreads. Men from the bar go to the sheriff, and a rock breaks the window. Men give Meyers a drink and ask what he found. Kirby Dawson (Bruce Cabot) arouses the crowd and leads them to the jail. The sheriff tells the crowd there is no proof of guilt and tells them to go home; but someone hits him with a tomato. Meyers throws tear gas and closes the door; but men break in with a battering ram, tear up the office, and set it on fire. Katherine heard Joe was arrested and arrives to sees Joe in the burning jail before she faints. A man throws dynamite.
Papers report the kidnappers were caught. Joe tells his brothers Charlie and Tom (George Walcott) he saw the newsreel and wants the lynchers prosecuted. The district attorney (Walter Abel) prosecutes 22 people for murder, while the defense lawyer (Jonathan Hale) blames the state for not protecting Wilson. The prosecutor questions witnesses, but even the sheriff cannot identify anyone. The judge ejects one loud person and sentences another for contempt. The prosecutor says that 6,010 persons have been lynched in the United States, and only 765 had a trial. Wilson listens on the radio. The newsreel is shown as evidence, showing who started the fire and identifying many. Katherine testifies she saw Joe in the burning jail but can only assume he died. The defense moves for dismissal, because no corpse was found. The judge testifies he received a letter with a ring that Katherine identifies as Joe's, but she sees the word "mementum." One woman confesses. Tom tells Joe he is lynching them, and Katherine pleads with Joe not to kill 22 people; but Joe insists on revenge. Katherine says she won't marry Joe, and he walks out. The jury acquits two but convicts the others. Joe Wilson comes into court and tells the judge his faith in justice and his country was burned. He hopes for a future with Katherine, and they kiss.
Made by a director who fled Nazi Germany, this story explores the dangers of mob violence in emotional revenge, which is then mirrored by Wilson's desire for revenge against them. The dangers of capital punishment are exposed.