Based on a historical novel by Elliott Arnold, a veteran learns Apache to try to make peace with Cochise so the mail can go through Arizona.
In 1870 the Apaches have been at war with Americans for ten years. Tom Jeffords (James Stewart) helps a dying Apache boy in the desert. Apaches led by Geronimo (Jay Silverheels) capture Tom and then ambush and kill five Americans.
In Tucson, Tom tells Col. Bernall and others what happened. He says the Apaches will not be defeated easily and refuses to scout. Tom tells Milt Duffield (Arthur Hunnicutt) he will get the mail through by learning Apache from Juan so he can speak to Cochise.
Tom rides alone into Apache country. He asks Cochise (Jeff Chandler) to stop attacking mail carriers. Cochise respects his bravery but suspects Americans. Cochise lets Tom visit secluded Sonseeahray (Debra Paget) before her ceremony. She sees him shaving, and they talk. Cochise tells Tom they will let the mail go through.
Tom announces the change and bets Ben Slade (Will Geer) that five men will return. Milt volunteers to go first and makes it back. Apaches attack troops with men hiding in wagons and kill fifty soldiers. Americans suspect Tom of spying. Tom wins the bet but is about to be lynched when Gen. Oliver Howard (Basil Ruysdael) releases him. Howard wants to make a treaty with Cochise.
Tom goes to Cochise and while waiting spends time with Sonseeahray. He kisses her. Cochise returns and discusses a treaty with Tom. In a ceremony Sonseeahray chooses Tom, who tells Cochise he wants to marry her. Cochise says it will be hard but agrees to speak for him. They are to be married. At night Tom is attacked by an Apache and fights him off. Cochise shoots the attacker for his betrayal.
Tom returns with Gen. Howard. After four days they meet with the chiefs, and Howard answers questions about the treaty. Geronimo challenges Cochise, who breaks an arrow and says he will try peace for three months. A majority stays, but the rest leave with Geronimo. Howard agrees to the 90-day armistice to test the peace.
Tom rides with a stage that is ambushed by renegade Apaches. He escapes to send smoke signals, and Apaches rescue them. Tom weds Sonseeahray in an Apache ceremony. Cochise says they will protect whites. Tom and Sonseeahray are happy. Ben Slade’s son arrives and says two horses were stolen. Slade and others ambush them, wounding Tom; but Cochise kills several. Tom finds Sonseeahray dead. Cochise won’t let him take revenge. Gen. Howard tells Tom that Americans now have the will for peace.
Written by black-listed Albert Maltz, this western shows the Apache viewpoint and thus exposes the racism of the European Americans. In violent circumstances making peace is a great challenge requiring much courage and patience. This fictionalized version of history makes the story dramatic and didactic.