In 1942 North Africa, the Allies recruit an anti-fascist officer as a code-breaker. The Americans discover that Johann von Rheiner is a royal prince. They recruit him but he doesn't help them much until Rommel is recalled. Then he opens up with all the information they need. His crime was to shoot the captain who threatened to rape a French woman and murder her children. He escaped to enemy lines. Captured by an Australian, he was incarcerated by the British, who handed him over to the Americans. He spends months as a POW. During his stint in the box, he gets to know intelligence officer Stanley Morris. Matching wits, the two become friends. Morris convinces Colonel Marshall to give Rheiner a chance. As a radio operator and master spy, Rheiner always fights on the side of the good, like Zorro against the Nazis. Meanwhile, he beats the Americans at their own game. In Chicago as a POW, he escapes. Camouflaged, he befriends Maria, the daughter of the colonel who turned him. He agrees to work with the colonel, but the FBI and secret service threaten his life. Maria rescues him, and he teaches cryptography in the Army training school for six months. The Americans bring him back to Europe with them. Rheiner survives many exploits till the end. Then he must face the Gestapo.