Luke Kayenta and his childhood friend Nantai Riggs are young shepherds of the Navajo reservation in Arizona. They volunteer for an experiment: to come up with an uncrackable code based on their language to be used by the US as it enters World War II. They fly into New York to join the spy agency the Office of Strategic Services (OSS). While on the airfield, Luke catches sight of a young woman. He is first enchanted, then heartsick when he finds that Kitty Charante is the devoted wife of his Canadian RAF pilot and instructor in espionage. Their paths will cross again.