Two worlds collide in this love story. The daughter of a pastor on a wagon train crosses paths with the son of a Mormon bishop. The Fancher party is a wagon train that is crossing Utah on the way to California. The Mormons don't want the gentiles to stop. The sight of women in men's clothing is disturbing for them. Several other personal reasons cause the Mormons to want the group to move on. Bishop Jacob (John Voight) calms the group down, but instructs his boys to keep an eye on the group.
Both the pastor of the wagon train, and the Mormon Bishop Samuelson praise God, but for entirely different reasons. Bishop Samuelson believes the train has been delivered to them to seek justice. The Fancher party believes they have been delivered by God. In the middle of all the discord, Emily (Tamara Hope) and Jonathan (Trent Ford) are falling for each other. The Mormons are led to rise up against the party, and kill them all by Brigham Young (Terence Stamp). They use a local tribe of Indians to fulfill what they believe is God's will. Jonathan stands up to his father, and tries to convince him to stop the massacre. He is imprisoned for his objection.
The Fancher party is able to defend themselves against the Indians. The Mormons must step in to complete the murderous plot. They are told to kill anyone who can speak. The leader of the Mormons, John D. Lee (John Gries), leads the party into an ambush. They are all brutally murdered. Johnathan has escaped, but arrives too late. When he gets to the site of the attack he finds everyone dead, even his Emily. She was killed by his very own father. Later on in 1877, John Lee receives justice. He is killed for his part in the bloody massacre. The Mormon leader, Brigham Young, denies any connection to the horrible slaughter of the Fancher party.