Sky Bandits(1940)

Sgt. Renfrew and Constable Kelly go aloft to search for a plane missing with a shipment of gold from the Yukon Mine Company. Inventor Speavy has devised a power ray which disrupts electrical impulses, and Morgan and his gang of crooks has brought in Prof. Lewis to increase the ray's range, telling him he's helping the government develop this new weapon. Speavy spills the beans to Prof. Lewis and his daughter Madeleine,and Morgan threatens to implicate them in his crimes unless they cooperate. Morgan kills Speavy when he tries to warn Renfrew, but when Madeleine stows away on board the doomed plane Renfrew is piloting, will the crooks be able to make Prof. Lewis use the power ray to bring the plane down?