From librivox.org:
The year is 1871, and wealthy ranch owner Jane Withersteen is in trouble. She has incurred the displeasure of her Mormon church leaders by refusing to marry a church elder and by befriending Gentiles (non-Mormons). In rides Lassiter, the quintessential Western hero: mysterious, purposeful, a deadly gunslinger, but with an unexpected streak of gentleness. While Lassiter is assisting Jane at the ranch, her friend and rider Bern Venters is having an adventure of his own in the Utah canyonlands. Riders of the Purple Sage is a story of heroism, love, brave men and strong women, good dogs and fast horses. And who is that Masked Rider?