When word reaches a U.S. Cavalry command that an Apache chief's son is planning an attack on Fort Yuma, a column of soldiers led by Lt. Ben Keegan is sent to deliver ammunition and supplies.

Accompanying them is missionary Melanie Crown, an educated and enlightened woman from the East who despises prejudice and strongly believes everyone can live together in harmony, and the sergeant's sister, Francesca, whose mutual attraction with Keegan is complicated, considering his views.

Keegan survives and experiences remorse for his beliefs, while Melanie and Jonas intend to set an example for the others how to co-exist in peace.

Geoffrey Shurlock told producer Howard W. Koch that it contained "sadism and excessive gruesomeness".

To get a seal, Koch allegedly reduced the number of killings from 24 to 10, although in fact there are still considerably more than 10 onscreen deaths in the amended version.