The Oro Grande Mining Company has a policy of shipping gold on buses, which have proven disastrously vulnerable to thieves. In order to protect the gold from falling into the wrong hands, the Three Mesquiteers — Stony Brooke (John Wayne), Tuscon Smith (Ray Corrigan) and Lullaby Joslin (Max Terhune) — convince the company to ship the gold on a plane they have recently purchased. The thieves, however, refuse to be outsmarted, and take to the air to do battle with the Three Mesquiteers.