Fitness center owner Ekaterina Turinina was found dead in her own bathroom. The investigation establishes that before her death, she had a serious quarrel with her daughter Julia, because of her fiancé Konstantin Rakov, who had a connection with a rival firm Turinina, who had long wanted to buy her business. Catherine considered him a swindler and offered him money so that he would leave her daughter alone. But Konstantin did not take the money. A quarrel with her mother served as an excellent motive for murder for Julia, and she is arrested.

The educational center for gifted children shook with horror: in an instant, the educational institution lost two employees - the director of the center, Alexander Vorobyov, and the psychologist Kira Mozheiko were killed. The detectives established that Alexander and Kira were lovers. Who could benefit from their death? Perhaps the true target of the criminals was not Vorobyov at all, but Kira, without whose recommendation not a single child could enter school.

Amina Tong, a student of the Faculty of Higher Mathematics and Cybernetics at Moscow State University, who came to study from Ulan-Ude, was found dead. All information from her computer disappeared without a trace. In the course of the investigation, it turns out that the girl, together with her classmate Yura, developed a program to predict the results of races on the races, and together with another student she played in a casino using her own system for calculating the probability of winning. The fact that, shortly before the death of Amina, Yuri sold the program to a certain Kirill, a daring gambler who attracts talented students to work on hacking and adjusting the list of results of races, comes up.