During the Civil War, a band of soldiers-of-fortune, led by Clyde McKay, infiltrates a town occupied by the Confederate forces of General Hood. After causing a diversion, McKay's group brawls with Confederate soldiers and manages to penetrate General Hood's headquarters. The general's aide, Captain Lynch, is disarmed and the general is made prisoner. However, the whole action is shown to be an exercise, planned by General Hood himself, to test the skills of Clyde McKay's group of six hand-picked mercenaries. It's true the six men are unsavory characters, bandits, killers and convicts but that's exactly what General Hood needs for his secret mission behind Union lines. Specifically, the Confederacy, which is short of cash, needs Union gold in order to continue the war. According to Captain Lynch, the Union is hiding an enormous sum in gold coins among dynamite sticks in an arsenal found in a Union stronghold. Clyde McKay's group, with occasional assistance from Captain Lynch, is to infiltrate the Union stronghold and steal the gold. McKay receives an advance payment for his services from General Hood. When he asks about his men's shares, in case they would be unable to return and collect the rest of the payments owed to them by the Confederacy, Captain Lynch replies that McKay should kill his men and return alone. Hence the Italian title of this film (translated into English it means: Kill Them All and Come Back Alone).