The war has turned against Germany. Development of the Nazi “wonder weapons” lag. Hitler demands elements of the American jet engine prototype, allowing his scientist to leapfrog ahead. Because of his anonymity, Abwehr intelligence deskman Delp will carry out the theft. He must recruit his conspirators from Nazis residing within the US, possibly with the help of fascist Mexican rebels.
The war has also turned against American-born Mark Stark. He seethes because his immigrant family has been incarcerated in the “enemy alien” roundup. Stark’s protests result in his internment alongside Delp, who has been apprehended while recruiting at an underground German American Bund meeting. Stark, now a disillusioned citizen, escapes the detainment camp with Delp.
Delp’s band, pursued by a rogue lawman, reaches Brownsville, Texas, site of the jet testing. Stark, inveigled into aiding Delp’s espionage, becomes involved with a war refugee. With the authorities closing in, Stark must choose between his family, his nation, and the woman he loves.