The legend says: whoever falls in love with a mermaid is doomed to death. Leia is the daughter of a petty baron from the provincial nobility. The estate where she lives with her parents and older sister is surrounded by impenetrable taiga forest, about which peasants have created legends for centuries. The forest is both a breadwinner and a dangerous neighbor. The old people know that in the thicket, in the muddy waters of the lake, evil spirits live - treacherous mermaids. What will a meeting with the merpeople bring to Leia and her family? Is it true that they are cruel, unprincipled creatures, or did their notoriety make the mermaids bare their teeth? Monks, peasants, robbers and aristocrats - all will be connected with a mysterious ancient cult, glorifying life where death reigns.