Six months of rustling was taking its toll on Jim Goodnight and the other ranchers in the Tuscarora Cattlemen's Association. That's why he sent a telegram to devil-may-care Rainbow Ripley and his grumbling sidekick, Grumpy Gibbs, the best range detectives the country had ever seen. When Ripley and Gibbs arrive in Crazy Horse, Nevada, they are approached by Dan Slack, with an offer to pay twice what the cattlemen were paying if they would work for him guarding the railroad spur to the Buckskin Mine. To the cattlemen's dismay, the detectives agree to take Slack's offer. Now someone is trying to kill the detectives. With angry cattlemen, clever rustlers, and mysterious activity with the mine and railroad, there is no rest for anybody. Ripley and Gibbs are in rare form. They may be wild, reckless, and downright ornery, but they will get the job done.