A professor invents a radium tube that makes internal combustion engines stop running. He and his invention are captured by a gang of robbers. A federal agent is sent to rescue him.

A Professor has an invention that will bring down planes causing them to crash and Dawson is forcing him to use it on those carrying money. When Tim arrives to investigate he is mistaken for a noted outlaw. So he assumes that identity to force Dawson to make him a partner. But just as a plane bringing Tim help is arriving, his true identity is revealed and while he is a prisoner, Dawson forces the Professor to start his machine.—Maurice VanAuken <[email protected]>

Remade as "Sky Racket", a non-western with Herman Brix/Bruce Bennett and than as a Renfrew of the Royal Mounted northwestern as "Sky Bandits" with Jim Newill.Lots of other versions of this wherein the heroine's kidnapped father is an engraver or diamond cutter or something forced to ply his trade in the interests of the gangsters. In this one, G-Man Tim Caverly is sent to the desert country to investigate mysterious crashes of airplanes carrying money, bonds and other valuables. He discovers that a mob led by Dawson and Kincaid are holding captive the father of Natalie Brent. Seems that the good professor has invented a powerful radium tube, which controls electrical impulses, and D&K Inc. are using his invention to cause plane crashes so they can plunder the wreckage. This one looks good until Tim parks his Stetson and dons an Amelia Earheart leather flying helmet and takes to the air.—Les Adams <[email protected]>