powered by AFI
Forest Service employee Charlie Carter tries to alert his colleagues to an infestation of a destructive tree moth, but lumberman Bill Wright cuts the telephone wires to stop him. Meanwhile, Gene Autry, who is riding with his friend, Joe Lucas, shoots at a mountain lion, and Wright takes advantage of the shots to kill Carter. When Gene finds Carter's body a few minutes later, he assumes that one of his shots was responsible for his death. At the inquest, Carter's death is ruled an accident, but Carter's daughter Helen is angry that Gene will not be punished. Later, a distraught Gene sells his sportsman's camp to his caretakers, Abner and Loie Weaver, and gives the money from the sale to Helen. Then, while riding through the woods, Gene discovers the moth infestation. Again, Wright tries to prevent a report from reaching the authorities and pushes a boulder off a cliff toward Gene. Champion, Gene's horse, senses the danger and saves Gene, but the boulder almost hits Helen and frightens her horses. After Gene stops the runaway horses and drives her home, Helen apologizes for her behavior at the inquest. Gene finally reports the moth infestation to the forestry department and accepts a job supervising the aerial spraying of the forest with DDT. He also learns that his rifle, a farewell present from his former colleagues at the forest service, had been tampered with as a joke and could not have killed Carter. The forest is quarantined, which angers Wright's employer, Henry Mitchell, who has a contract deadline to meet. Mitchell and his men then set out to convince the ranchers that the DDT will kill their livestock and turn public opinion against the spraying. Later, when Joe, who is flying one of the crop dusters, crashes his plane, Gene angrily lectures him about his drinking, but softens when he learns that Joe's beloved wife died while he was overseas. Because he knows they are using safe levels of DDT, Gene is surprised when Dr. Daniel Chadwick reports that many dead animals were found after the spraying. Recalling that he heard a strange plane during the night, Gene begins to investigate the poisoning. Joe, meanwhile, sneaks into a locked building on Mitchell's property and finds a plane with remnants of DDT on it. After Wright discovers Joe and shoots him, a badly wounded Joe takes refuge with Helen. From Joe, Gene learns about Mitchell's plane and accuses the lumberman of framing the forestry service. Mitchell challenges him to prove it, but when Gene arrives at the lumber company, Mitchell has replaced the plane that Joe saw with a broken-down plane. Mitchell then imprisons Gene in the building and, while trying to escape, Gene discovers the cans that Mitchell used to store the DDT. Later, Mitchell sets a trap for Gene. Joe then tries to warn his friend from the air, and failing that, crashes his plane into the cabin where Mitchell and his associates are waiting, and they all die in the crash. His job finished, Gene temporarily leaves the forestry service and, as he rides away, sings Joe's favorite song in tribute to his loyal friend.