When professional soldier Frank Cort arrives in Vienna with a beautiful blonde, Jake suspects that he has unfinished business with Vasamubo, deposed premier of Upper Namba and with General Gundarson. The General with his United Nations Forces is the only man to defeat Cort, who commanded an Army of mercenaries for Vasamubo.
Jake Webster is startled to meet in Vienna Charley Stokes, whom he saw killed on a beach in Albania after the pair had blown up a power installation. Charley explains that, though seriously wounded, he was saved by Elga Compani, number two official in the Albanian Secret Police and is now married to Charley. Jake begins to suspect that Charley and Elga are still loyal communists.
Jake is hired by Aline Masterson of a New York museum to recover the Royal Crown of Bosnia, stolen from her outside the Hofburg Museum. Through underworld contacts Jake delivers the pay-off money to a hijacker. When Jake is knocked unconscious at the rendezvous site, both he and Aline are suspected of being confederates.
When Floyd Macklin, an American black marketeer, escapes from a Black Maria, he vows to kill prosecutor Hans Eckert and Major Caldwell, the men responsible for his 20-year sentence. Jake sets up a meeting with Macklin at the Prater Amusement Park, but Caldwell and Lt. Hoffman arrive with the Viennese police before Jake can capture his man. Macklin rushes away and Jake is jailed as a suspect in engineering Macklin's original escape.