Set during WWII, this taut and suspenseful espionage outing chronicles the courage of a brand-new cadre of specially trained American O.S.S. agents who parachute into France to destroy the vital Corbett Mallon tunnel to stop the German invaders from shipping supplies to their troops. One of the spies is a woman, and this bothers the group leader, who doubts her abilities. She soon proves herself, and the two embark on several exciting adventures before and after the completion of their mission. Along the way, the two manage to fall in love. Unfortunately, their commitment to duty is necessarily greater than their love and one of them will make a great sacrifice.