When the plane owned by the "Yukon and Columbia Mail Service" crashes, RCMP Sergeant Renfrew (James Newill) and Constable Kelly (Dave O'Brien) suspect murder. Their suspicions are confirmed when Renfrew finds the control stick has been jammed, forcing the plane to fly in one direction until the gas ran out. Mine owner Louise Howard (Louise Stanley) reports that her superintendent is missing. The Mounties find him murdered and that too has been made to look like an accident. A new mail service pilot, Bill Shipley (Warren Hull), arrives. He had gone to training school with Renfrew but had been cashiered for misconduct. The Mounties discover that Raymond (Karl Hackett), who had been working for Louise, really owns the flying line managed by Yuke Cardoe (William Pawley.) They find proof that all the gold from the mine isn't being turned over to Louise, and suspect that Raymond and Yuke are stealing the gold and shipping it to Seattle by plane. Renfrew sets a trap and Yuke and Raymond try to escape in their plane.