Hop Harrigan: America's Ace of the Airways: Hop Harrigan, a top Air Corps pilot, leaves the military and he and his mechanic, Tank Tinker, open up a small charter air service. They are hired to fly an inventor, Dr. Tabor, to his secret laboratory, where he is working on a new and powerful energy machine. However, a mysterious villain named The Chief Pilot is determined to have the new energy machine for his own purposes and kidnaps Dr. Tabor.