The Western novel "Riders of the Purple Sage" continues in its sequel from 1915 "The Rainbow Trail". The novel depicts the difference between older Mormon community and new generation of Mormons who stand against the polygamy. John Shefford, a disillusioned preacher, hears the story of Jim Lassiter, Jane Withersteen and their foster daughter Fay Larkin, who have been stuck in the Surprise Valley for many years. Without even seeing Fay, John fells in love with her, and he decides to head out West and rescue her from the life of imprisonment.
Will his mission be successful? What type of evil practice will he witness? Who will prevail in this battle between the generations?