Count the pulp magazine conventions in this one: a mysterious invention, disappearing airliners, a mysterious masked villain, a stalwart hero who is a pilot and an inventor, his two buddies who provide a little (very little) comic relief, and a pretty stewardess who is the hero's girl friend. Oh, yes, and the FBI man who appears in the nick of time and helps the hero save the day. Somehow it all adds up to an entertaining B movie, so long as you don't look too hard for plot holes or object to pretty basic production values. Stock footage of vintage 1930s airplanes provides another point of interest.