It is the year 1936 and the Spanish Civil War is raging. When the German commander of an international brigade is badly wounded he gives his five comrades a message which he divides up and secretes into in five cartridges. All five shells must reach the battalion in order for the message to be relayed. But Frenchman Pierre can’t bear the heat of the Sierra. When he leaves their hide-out to drink from a well he is hit by an enemy bullet.

The film centers on the story of newlyweds Inga and Heinz. Heinz works in the western sector of Berlin. A gang of crooks involved in various shady dealings tries to draw Heinz into their dark affairs. However, after accidentally learning about the "activities" of his "friends," Heinz informs the police about the impending crime. The gang is arrested.

Spain 1936: Despite the victory of the Popular Front, nothing has changed for the peasants; the grandees continue to oppress them. The poor peasant son Pablo fights back and encourages the others to demand their rights. The grandees flee. Students from Madrid arrive and help the rural population to democratize. Pablo falls in love with Magdalena and learns to read and write from her. When Franco begins his bloody attack on the young republic, they defend the village together. When Magdalena dies in a bombing raid by German planes, Pablo begins to hate the Germans. However, fighting together with the International Brigades, he realizes that there are other Germans too, and that they share a common enemy.