Sheriff Jefferson Mosby, of the Kentucky Mosbys, is assigned by the district inspector of Arid, a small town in Nevada, to investigate a dangerous region known as Cactus Flats, which is infested by outlaws bent on driving out the homesteaders. In Cactus Flats, he meets Molly Miller and Danny Duggan, the last of the homesteaders, and learns of the cruel way Buck Connor, the mayor, orders them to vacate every now and then. By means of disguise, Mosby infiltrates Connor's gang and catches Connor with the goods; then, with the aid of Molly and Danny, he arrests the culprits. In the end, in spite of the inspector's advice not to trust a woman, he decides to take orders from Molly for the rest of his life.
The film was copyrighted under the title, Two Fisted Jefferson. The working titles of this film were Sparks of Flint, Flints of Steel and Under Orders.