During the Spanish Civil War, an American language teacher, Robert Jordan, who lived in Spain during the pre-war period, fights in the International Brigades against Francisco Franco's forces. An experienced dynamiter, Jordan is ordered to travel behind enemy lines and destroy a critical bridge with the aid of a band of local anti-fascist guerrillas. The bridge must be blown up to prevent enemy troops from traveling across it to respond to an upcoming offensive against the fascists.
Jordan meets an old man, Anselmo, who is a guerrilla fighter who will serve as Jordan's liaison with the local guerrilla fighters. Anselmo leads Jordan to a group of Republican guerrillas who are led by a middle-aged man named Pablo. Jordan falls in love one of the guerrillas, a young woman named María. María's life was shattered by her parents' execution and her gang-rape at the hands of the Falangists (part of the fascist coalition) at the outbreak of the war. Jordan has a strong sense of duty, which clashes with the unwillingness of the guerrilla leader Pablo to commit to helping with the bridge-blowing operation, as it would endanger himself and his band. At the same time, Jordan develops a new-found lust for life which arises from his love for María. Pablo's wife Pilar displaces Pablo as the group leader and pledges the allegiance of the guerrillas to Jordan's mission. However, when another band of anti-fascist guerrillas, led by El Sordo, is surrounded and killed in a desperate last stand, Pablo destroys Jordan's dynamite detonation equipment, hoping to prevent the bridge demolition and thereby avoid fascist reprisals on his camp. Later, Pablo regrets abandoning his comrades and returns to assist in the operation.

Directed by Sam Wood
Starring Gary Cooper, Ingrid Bergman, Akim Tamiroff, Katina Paxinou, Joseph Calleia