Pierre (12) is the victim of a recurring nightmare he has had since infancy. The trauma of the dream has caused him to find solace in his daily vigorous sojourns through the mountain wilderness that surrounds his family’s remote cabin in the 1840s. The cabin is in Ute territory near the Oregon Trail. The family is French, and Pierre speaks no English. On one outing, he meets Ohanzee, a Ute boy his own age. They are twelve when they meet. Defeating a bear together, the two become blood brothers.

When a Ute raiding party, in which Ohanzee is an unwilling participant, kills Pierre’s parents, Pierre escapes into the wilderness to survive alone with the help of Ohanzee who brings him food.

Later, Pierre and Ohanzee witness the slaughter of Ohanzee’s tribe by white men. The two boys, now thirteen, must face the wilderness with none but each other to rely upon.

The two find a cave in a lost valley. The cave becomes their new home. When the two boys are sixteen, they save the life of a young Bigfoot, Tohopka, who later finds them at the cave and befriends them.

Six years later, a woman, Effie, escapes from a wagon train traversing the Oregon Trail where a fanatical preacher has killed her husband because of his lust for her. After her escape, she is alone in the wilderness where she collapses from exhaustion. Tohopka finds the woman and carries her to the cave. Pierre and Ohanzee care for Effie until she recovers. Effie’s late father was French, and she is able to speak to Pierre in his native tongue. In desperation, Effie takes a fur jacket and some food from the cave during Pierre and Ohanzee’s absence and returns to the wilderness where she is found and captured by the preacher and his henchmen. Pierre and Ohanzee track Effie back to the wagon train, but thinking she is all right, Pierre and Ohanzee return to the cave.

Effie will later return to the valley after killing the preacher and enduring a perilous journey back from Oregon.

Ohanzee meets a Shoshone girl, Wokaih, and falls in love. Her father, the chief, is against their relationship, and Wokaih escapes the tribe to live with Ohanzee in the valley. Her action incurs the wrath of her father who sends a war party to bring her back.

White men come to kill Pierre and Ohanzee. Shoshone also come to kill them. The boys, with the help of Tohopka, defeat them all. Finally, the white men and the Shoshone combine forces to kill the two. Pierre and Ohanzee use the terrain and fauna to defeat all comers and become legends among the whites and Shoshone alike.

The two boys’ desire to survive and unite with the women who love them is only realized after an epic struggle by both couples against two cultures.