An attractive Russian woman Katya is a literary editor. Trying to send a manuscript of a famous Soviet scientist to a British publisher, Barley Blair, Katya unwittingly draws them both into the world of international espionage. The manuscript, the content of which is enough to disrupt the global balance, is intercepted by Western intelligence. Blair is recruited to the Soviet Union for the production of new information about the mysterious manuscript. But when Blair meets Katya, he has to choose between his mission and passion for a woman whose devotion to her country is unshakable, as for Blair himself.