Sent to protect a deserted U.S. outpost on the desolate frontier, Lt. John Dunbar finds himself alone in the vast wilderness. Slowly befriending the very people he was sent to protect the outpost from, the Sioux Indians, Dunbar comes to revere those he had once feared. But when the encroaching U.S. Army threatens to attack, he must make a choice, one that will forever change his destiny.