The setting is 1943 in the U.S. First Lady Eleanor Roosevelt requests former First Lady Edith Wilson to transport an important package. Mrs. Wilson is the courier of a champagne bottle filled with heavy water. She leaves from Washington via Burlington Northern train and then boards a Zephyr Express to Colorado. Her destination is unknown.
Mrs. Wilson's escort, an OSS agent, is murdered in Chicago. The Zephyrette aids her, but she is kidnapped. The bottle is also switched a few times.
Mrs. Wilson keeps her wits about her, and reaches her destination safely and with the champagne bottle intact.
