Danny's father has joined the Mormon religion back east, and they join a wagon train going to Oregon. The family knows nothing of his change of religion until after they are on the trail, too far out to return to civilization. They learn he has taken a second wife, and an outraged Ma puts all his belongings outside the wagon and tells him to go live with his new wife, because she will have nothing more to do with him. Being 'man of the house' falls to Danny. They meet a leathery-looking giant of a man, named Milenko, who will relieve Danny's driving of their wagon occasionally. They are traveling north of the Platte River. South of the river was a non-Mormon wagon train. By the time they reach Wyoming, they are attacked by Indians, and the wagons bounce so hard over the rough terrain that Claudia, Danny's sister, is throw out. She doesn't move. Danny jumps out to help his sister, and finds she has broken her leg. The fleeing wagon train is soon out of sight with a band of Indians still chasing them. A single Indian, Pico, comes upon Danny and Claudia, and makes them his captives. For days, with Claudia in pain from her broken leg, they rode south to the Navajo reservation where the Indian lives. Danny learns that Pico's father is a white trading post owner, and his mother is a Navajo Indian. They spend the winter sometimes at the trading post, but also at the hogan where Pico lives. When the springtime freight wagon-train comes to the trading post, the drivers offer to take Danny and Claudia back to Salt Lake City. Once there, Danny learns his father is dying. He finds him and is with him until he dies. They find Milenko, and he tells them Ma is in Wyoming,waiting for him to return - he had been searching for the two children all winter long. It is an exciting story set on a colorful background, and it shows how compatible people can be of other religons.