Swedish military attaché Stig Wennerström comes into contact with the US secret service at a party. After a trip to Moscow, he provides the Americans with valuable information about Soviet jets. But Wennerström is playing a double game. Lieutenant General Aratov, a Russian officer, approaches him and becomes his partner in shady dealings. For three years, the double agent game works. But then the Soviet secret service discovers that Colonel Wennerström is also working for the class enemy. The Swede is forced to spy exclusively for the Soviets from then on and goes to the American capital...