Bodyguard Evgenia Okhotnikova always believed that she and Aunt Mila had no relatives. But one day a young man appeared on the threshold of the apartment, calling himself the nephew of Lyudmila Okhotnikova. It turns out that the aunt had a brother who left the country a long time ago, and this young man is his son, who grew up in America. At first glance, the new cousin arouses Zhenya’s suspicions, and his stories seem implausible. Evgenia is sure that he is not at all who he claims to be. But Aunt Mila is fascinated by Konstantin. Zhenya’s attempts to expose the swindler lead to a quarrel, after which Evgenia is forced to leave her aunt’s house and live separately. Spying on a suspicious relative leads Evgenia to the outskirts of the city, where she finds Kostya dead. The arriving police squad discovers a strange object on his body - and only Okhotnikova’s special training allows him to timely identify the container with biologically hazardous material - a deadly virus...