Riders of the Whistling Pines

Forester Carter discovers a tussock moth infection that threatens the forest and the lumber profits. Henry Mitchell schemes to exploit the dying trees to harvest without restrictions. When Carter tries to report the infestation by phone, Mitchell cuts the line, forcing him to ride into town to alert authorities.

On the trail, Gene Autry and Joe Lucas, drinking, encounter a mountain lion and Autry fires at it. The close brush with danger pushes Autry to become more involved in forest affairs. The incident foreshadows the dangers to come in the forest.

Mitchell uses his last shot as cover to shoot Carter in the back, making it look like Autry's stray shot killed him. Carter collapses, and Autry becomes the prime suspect in the forester's disappearance. The deception triggers the inquest that will shape the community's response.

At the inquest, Gene is cleared of any charges and freed. He sells his forest camp and leaves the money to Carter's daughter, Helen, hoping to honor the fallen forester. Despite the relief, Autry decides to leave the area only to discover the moth infestation himself and vow to report it.

Autry is hired to run an aerial spraying program to kill the larva before the forest is destroyed. He involves his friend Joe in the operation, despite Joe's ongoing troubles with alcohol. The team prepares for the dangerous spray campaign across the woods.

Meanwhile, Mitchell hatches a plan to stop the DDT spraying by covertly applying a very potent poison to local livestock and blaming the sickness on the spraying. The scheme is aimed at turning locals against Autry and the spraying effort. The tension mounts as the plot unfolds.

As Joe rides to report the poisoning, Wright shoots him, leaving him gravely wounded. Helen and Dr. Chadwick work to save him, restoring hope that the spraying effort can continue. The incident galvanizes Autry and Joe to keep up the fight.

After recovering, Joe informs Gene about Wright's poison plan and the need to protect the spraying operation. Gene uses this information to rally the locals to support the spraying and to counter Mitchell's schemes. The alliance between Gene, Helen, and Dr. Chadwick strengthens.

Wright manipulates the locals into opposing the aerial spraying, creating a hostile atmosphere around the planes. Gene rides out to confront the protesters and verify Wright's treachery. He recruits some residents to verify the threat firsthand.

Wright has dismantled one of the planes and captures Gene and Forester Jerry, but they manage to escape and rush back to the airfield just in time for a brawl to save the aircraft. The sheriff arrives and breaks up the fight, confiscating weapons. The spray program hangs in the balance.

With the aid of Helen and Dr. Chadwick, Gene tricks Mitchell and Wright into believing he possesses the bullet removed from Joe and that it can be traced to Wright. They ride toward the shack where Gene is waiting, hoping to ambush him. The trap is set for the final confrontation.

Pete tries to cut a deal by confessing the truth, but the pursuit continues. Joe realizes he cannot catch Gene in time, so he heads to the airfield to intercept the final showdown. The chase tightens as loyalties clash.

In the climactic sacrifice, Joe flies toward the action and, realizing there is no one left to fly the plane if he is shot, crashes the plane into the shack, killing Wright, Mitchell, and himself. Gene survives and resumes the spraying mission. He looks toward a future of forestry work and marriage to Helen.