Maria and Andrey Bystrov are investigators of the Investigative Committee. Upon learning that her husband had cheated on her, Maria spitefully meets him with a former admirer. Soon she realizes that she is pregnant. The Bystrovs marriage is collapsing, but they have to conduct a new investigation together. Poisoned businessman. The poison was in a cake that his wife Elena had brought him from work: she explains that one of the patients left a dessert for her as a present. The suspect is quickly located. But when the matter seems solved, a new drama takes place in Elena's life. It becomes clear that she has a secret enemy who came up with a sophisticated plan of revenge. But Elena cannot remember who crossed the road ...