Sergius is a former priest who has been removed from service. Now he reveals crimes committed with the participation of dark forces. For Sergius, this is not only a fight against evil, but also a business: for every evil spirit he gets, he receives a good reward from good forces in the person of Aunt. Sergius does not shy away from earthly pleasures and from time to time gets into trouble, in connection with which police investigator Captain Katya Zemtsova comes on his trail. Katya is not ready to believe in the supernatural and suspects Sergius of committing terrible crimes. Together they will have to go a long way and learn to trust each other. Ahead of them are not only a battle with evil spirits (in the first season it is the Ghoul, Koschey and Kot-Bayun), but also the machinations of Katya's harmful and envious colleague, operative Krakin. With each solved case in the relationship between Katya and Sergius, mutual sympathy is more and more visible .