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.