Katya, a young librarian, believes in love, but her ideals are crushed by reality. After a string of disappointing affairs, Katya finally finds tenderness and understanding in the arms of her colleague, a journalist called Tanya. But then the First Department interferes: the state security services see this relationship as unacceptable for a Soviet woman.
Nikita Nekrasov is a scientist, a theoretical physicist who studies our world and other possible worlds. He refuses to make a choice between mathematics and physics, between one woman and another, as he ponders the existence of the multi-universe. At scientific conferences, attended by eminent foreign scientists and a rising younger generation of physicists alike, Nekrasov gets carried away debating the beauty of string theory. He attempts to explain to all of his women – Katya, the librarian, Zoya, the scientific secretary, Svetalana, the head of department – about the theory of his own polygamy, and the possibility of having enough feelings to satisfy everyone.