 A highly ranked Russian official, Boris Kusenov (Per-Axel Arosenius), his wife and daughter defect to America. Hoped to be a boon for their efforts battling the Cold War with Russia, the Americans soon find out that they have more to deal with than first thought, with Kusenov being less than cooperative, especially in regards to anything to do with a known leak in the French government, codenamed Topaz, which has seen top secret files leaked to those in Moscow. On discovering an agreement between the Russians and Cubans, agent Nordstrom (John Forsythe) enlists the aid of his friend, and French agent, Andre Devereaux (Frederick Stafford) who accompagny at that time his daughter Michèle (Claude Jade) at her honeymoon with journalist Francois Picard (Michel Subor). André accepts, but his wife Nicole (Dany Robin) is worried for him. After managing to get hold of some seriously damning papers from the visiting Cuban official Rico Parra (John Vernon), sneakily of course, a concerned Devereaux jets off to Cuba and catches up with his mistress Juanita de Cordoba (Karin Dor), who is now secretly involved with a local underground movement whilst also being involved in another way with Parra. He finds out and kills Juanita. Ever the jetsetter, Devereaux is now off home to Paris to get to the bottom of this whole leak problem. Michèle wants to reconcile her parents. Nicole cheats Andre after his cuban affair with the leader of the spy-ring "Topaz", Jacques Granville (Michel Piccoli). Francois goes on, to find out, who is "Topaz" and he interrogate NATO-official Henri Jarre (Philippe Noiret). A short time late Michèle finds the murdered Jarré - and Francois is missing...