The Rainbow Trail, also known as The Desert Crucible is the sequel to Riders of the Purple Sage by Western writer Zane Grey. Originally published under the title The Rainbow Trail in 1915, it was re-edited and rereleased in recent years as The Desert Crucible, restoring the original manuscript that Grey submitted to publishers.
The novel takes place 10 years after the events of Riders of the Purple Sage. The wall to Surprise Valley has broken, and Jane Withersteen is forced to choose between the Lassiter's life and Fay Larkin's marriage to a Mormon.
Both novels are notable for their protagonists' mild opposition to Mormon polygamy, but in Rainbow Trail this theme is treated more explicitly. The plots of both books revolve around the victimization of women in the Mormon culture: events in "Riders of the Purple Sage" are centered on the struggle of a Mormon woman who sacrifices her wealth and social status to avoid becoming a junior wife of the head of the local church, while "Rainbow Trail" contrasts the fanatical older Mormons with the rising generation of Mormon women who will not tolerate polygamy and Mormon men who will not seek it.