Secrets of Investigation (Russian: Тайны следствия​ⓘ) is a Russian television series filmed from 2000 through 2018. The format of the series features 2 to 4 50 minutes episodes arranged into story clusters. The television series follows the work of a Chief Detective Maria Shvetsova (played by Anna Kovalchuk) of a St.Petersburg Saint Petersburg District IC Investigative Committee of Russia. As of 2021, the series contains 180 episodes (of 21 seasons).
 The Office of the District IC at one of districts of Saint Petersburg investigates the most difficult crimes. Possibly, many of these affairs would have remained unsolved, if not for the talent and sharp senses (including sense of humor) of the Chief Detective Maria Sergeevna Shvetsova and her team.
 Secrets of the investigation 9
After the reorganization of the prosecutor's office a major problem for Shevtsova is still Nikolai Filonov. He is doing utmost in his power to avoid or get rid of complex and unsolved cases in his district.
 District IC Investigative Committee of Russia headed by Nikolai Filonov (Senior Advisor of Justice) would long have turned into the organization for the collection of statistical crime related data, if not for Maria Shvetsova and her colleagues – experienced homicide detectives Vinokurov & Kurochkin. Maria is not afraid to take the initiative and, in spite of irritation of Vinokourov, she always prefers to go to the scene herself in order to interview witnesses and gather evidence. And often, it is only she whose watchful eye manages to catch the details that eventually lead to solving crimes.
Without her participation of the strange death of the director of thriving "Autlink" would have been qualified as a simple accident. However demanding Shvetsova insists on forensic expertise and establishes the true cause of death of Nikanorov.
Shvetsova used to always trust her sensitive intuition that helps her, even if the mere facts are not enough. Thus, having begun the investigation of the murder of the owner of the collection of antique coins Florinskaya – she pretty quickly discovers that the prime suspect, whose "candidacy" is insistently being suggested to her by the relatives and friends of the deceased, has actually nothing to do with this crime.
Maria Shevtsova always tries to see into the case from different sides, and then the true motives of the murder come to the surface. In some cases, the work of the investigator comes to scrutinizing all evidence collected at the crime scene; and sometimes becomes a real puzzle. However, by restoring the true picture of the crime, Maria manages not only to find the culprits, but also to prevent a new crime.
Meanwhile, Maria's boss Nikolai Filonov remains concerned solely with his own career growth. For the sake of promotion he is ready to pull the brakes on any "uncomfortable" case. A principled and stubborn nature of Shevtsova's may cause considerable inconveniences to such superior; so each case for Maria Sergeevna may be the last.
 The body of Vygotsky, a CEO of an esteemed beer brewery worth $500 million, is found on the doorsteps of a restaurant. His wife and mistress will fight for the vacant director's chair. Maria has to figure out which one of them is involved in the murder. Fortunately, Shevtsova is always readily helped by her colleagues – experienced homicide detectives Vladimir Vinokurov and Fedor Kurochkin. Further on the Petersburg investigative committee will discover a strange crime – the murder of a former skipper Glebov poisoned by an unknown neuroprotective drug. In her personal life, Maria has full support of her family – her loving husband Dmitry Luganskiy and daughter Zlata. Owing to their support, as well as to her outstanding abilities Maria never succumbs to the difficulties of investigation of the most difficult crimes. In some cases a new employee of the Committee, investigator Lyudmila Kolinskaya is actively involved. She had been personally employed by the boss of the investigative committee Filonov, the man relations with whom for Shevtsova are still uneasy.
 Under the leadership of Kovin Maria finally gets the required degree of freedom, that for so long was dreamed of at the times the superior chair was held by her longtime foe Filonov. Assessing the benefits of the new situation, she is reconciled to the fact that her own merits as a leader again, have not been evaluated "at the top ", and with her head dipped in the cases, the flow of which does not dry out for a minute – she continues investigating: murder and other crimes caught in her field of vision, is almost everything that absorbs the attention of Shevtsova... until her husband Luganskiy has been sent abroad for a six months business trip...
 Shvetsova continues to work as a public defender at the Zanevsky SC, simultaneously helping her first husband Andrew with a divorce, during which she discovers signs of fraud by his new wife, and also tries to guide the girl Liza on the right path and maintain relationships with children. Meanwhile, the new investigator Boris Shipov, who has his own methods and ideas about the work of the investigator, is being transferred to Zanevsky Investigation Center from Rostov.
 On May 1, 2018, filming of the 18th season.
 In the new season, a brilliant investigator Maria Sergeyevna Shvetsova will have to sort out new convoluted crimes. Find out which guest poisoned a major businessman Lunyov's birthday, find out where an unknown mass grave originated in the city center, call the cold-blooded killer of a famous artist to answer, catch the criminals holding the whole area in fear and much more.
 This season there are scenes of memories of various episodic characters, which has not yet happened.
 On October 6, 2018, filming began on a spin-off and prequel on the series Secrets of Investigation. Last century.