The dashing Captain Hugh "Bullshot" Crummond - WWI ace fighter pilot, Olympic athlete, racing driver, part-time sleuth and all round spiffing chap - must save the world from the dastardly Count Otto van Bruno, his wartime adversary. And, of course, win the heart of a jolly nice young lady.

When odd reports are received through official channels stating that the President of the United States is being held captive on a secret international moon base called Vegan and that he has been replaced on Earth by a clone, the US Marshall Service immediately sends their 'best' man, Dix, on the mission.