Museum worker Varvara Popova lost her 22-year-old son Misha. She wants the Beagle Agency to keep him under surveillance. It soon turns out that Misha simply fell in love. The object of his passion was a certain Olga Burlakova, 28 years old, the widow of the famous antique dealer Viktor Burlakov, who was killed in his apartment a month and a half ago. Varvara Dmitrievna demands that Rostovtsev find incriminating evidence on Olga. She is sure that this woman, whom her son contacted, is involved in the murder of her husband. Varvara Dmitrievna does not yet know what shocking truth about her son she will have to hear.
An attempt was made on businessman Marat Shaikenov. Shaikenov believes that this is the same sniper who has been keeping the entire city in fear for a month, committing more and more murders. Shaikenov turns to the Beagle detective agency with a request to find the sniper. Moreover, death now threatens not only him, but also his fiancée Ella. Investigating this complicated case, private detective Andrei Rostovtsev meets family psychologist Alina Belova, who, thanks to her professional experience, helps Rostovtsev identify the criminal. Rostovtsev invites Alina to become a member of his team.
Alina's fiancé, the famous journalist Dmitry Aristov, lost a flash drive with compromising information on Deputy Governor Stanislav Kravchenko, who, according to his wife Maryana, was involved in the murder of their housekeeper. The detectives, along with a new member of the team, 18-year-old Young, get down to business. One version replaces another, mysteries multiply. Thanks to Alina's professional instincts, she manages to figure out the true killer, whose name comes as a surprise to the whole team. After the successful completion of the case, Alina accepts Andrei Rostovtsev’s offer to become a full-time psychologist at the Beagle detective agency.