In the midst of the Cold War, a high-ranking Soviet official, Boris Kusenov, defects to the West, bringing with him alarming intelligence that suggests the Soviet Union is placing nuclear missiles in Cuba, potentially triggering an international crisis. To verify this critical information, the CIA enlists French intelligence agent André Devereaux to investigate. Devereaux's mission leads him to Cuba, where he must navigate the dangerous waters of espionage, dodging the watchful eyes of Cuban secret police and gathering the necessary evidence to confirm the missile placements. His investigation also reveals a network of spies, code-named "Topaz," an intricate web of deception that spans across different countries, adding layers of complexity to his task.

As Devereaux digs deeper, his personal and professional worlds collide, bringing tension and risk not only to himself but also to his family and associates. His journey takes him next to New York, where a crucial meeting with a NATO official is supposed to unfold. Along the way, the line between allies and enemies blurs, making trust a valuable yet scarce commodity. The stakes are exceptionally high, as the outcome of Devereaux's mission has the potential to influence global politics and the very fabric of international relations during one of the tensest periods of the 20th century. Through a labyrinth of espionage, betrayal, and secrets, the quest for truth tests the limits of loyalty and courage.