The story follows ex-GI Lucky Gagin, who arrives in the small New Mexico town of San Pablo with a singular aim: to avenge the murder of his wartime friend. He carries with him a valuable ring as leverage against the corrupt and wealthy gangster Frank Hugo, whom he believes to be responsible. Gagin’s first stop is a seedy hotel where he meets Pancho, a merry-go-round operator, who becomes his reluctant ally. In the bustling town square, during the Fiesta, Gagin also crosses paths with a naive but spirited young woman named Pila, who senses his troubles and is inexplicably drawn to him.

As Gagin maneuvers through San Pablo’s vibrant yet gritty environment, he encounters both threats and offers of help. FBI Agent Bill Retz pushes him to cooperate with the law for his own protection, while Hugo's henchmen lurk ominously in the backdrop, waiting for their moment to strike. Gagin finds himself teetering on the edge of violence and justice, all while grappling with his ethical dilemmas and personal vendettas amidst the chaotic celebration swirling around him.