New York gangsters, Mack the leader, Looie, Dopey and Don, who specialize in the protection racket, go west to ply their trade among the ranchers. Henry Hess, head of the Federal Investigation Department (and not called the FBI in this film) receives a call for help from his brother Tim, one of the many rancher/victims of the gang. Hess sends the FID's best man, Bob Blake. At the train station Blake meets Tim's daughter Jean, her uncle Joe Hess, her baby brother Tim and Braveheart the police dog. Blake, posing as a vacation visitor, arranges to stay at the Hess ranch. They ride there in Uncle Joe's car. En route they see Al Romero, an Hess employee who has stolen the payroll, being chased by Tim. Blake lassos Romero out of the saddle. Tim recovers the stolen money and also the stolen white horse he was riding, Starlight, Blake's horse that had been shipped ahead to the ranch by Hess. Rancher Scully sends notice that the gangsters (one of the very, very few westerns in which the henchmen can be called "thugs" by those who don't seem to know that the term used, by the producers, writers, directors, players and the printed cast in westerns is "henchmen") are on the way to his place. Bob, Tim and Dave ride to Sully's place before the gangster thugs arrive. Meanwhile, in an effort to pad the plot and running time, Bobby Hess wanders off and Braveheart the dog trots around awhile and finds him. Later, the gangsters stampede a herd, shoot Dave and capture Blake and leave him tied up in a cabin with Dopey and Don as guards. Starlight rushes Dopey and runs him off, while Braveheart assaults Don and chews Blake's bonds loose. Blake mounts Starlight, takes a a shortcut and overtakes Mack and Looie in their car.