The true story of the exploits of the RAF's (Royal Air Force) foreign legion battling the German Luftwaffe (Nazi Germany's Air Force) during the early months of 1941 during WWII before America officially entered the war at the end of the year when Pearl Harbor was attacked by Japan and Hitler declared war on the United States. The United States then drafted all of their airmen and fighter pilot aces into the United States Air Force for their own combat missions against the Luftwaffe

Brass Bancroft and his sidekick Gabby Watters are recruited onto the secret service and go undercover to crack a ruthless gang that smuggles illegal aliens.

In a Scottish sanitarium, a brilliant research psychiatrist works on a treatment for dementia praecox. He falls for his altruistic female lab assistant and they begin a passionate, tragic relationship.

When Barry Corvall discovers that his new bride is a possible enemy agent, he resigns from the diplomatic service to go undercover to route out an espionage ring planning to destroy American industrial capability.