Synopsis: 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, Tuscon Smith and Lullaby Joslin -- 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.