Collette Dugan, a French Resistance fighter working with British and American G2 intelligence sectors in London, receives a frantic radio message from her known Resistance friends in Calais. Crucial information about German troop and armament placement along the French coast needs to be extracted to help with the Allied invasion of Europe. Collette, along with two American Army Officers—Lt. Randall Becker and Lt. Jacob Miller—carry out a daring submarine raid to save the information before it's too late.

For Collette, her story ends here. But for Becker and Miller, this information leads them across the European theater to a small staff house in Salzenburg, Germany. There they meet a German Major, Hans Hessler, who offers the US Army an attractive proposition.

Only after the war ends do Becker and Miller discover that the Major has one more secret to tell—a secret hidden within a coder machine and linked back to the house in Salzenburg. But they're not alone and must move quickly before all is lost—including their lives.