Sociologist Katya Mitina travels to a remote river island to conduct a population census. This spot has a sinister reputation: in ancient times, it was home to a pagan shrine, and later, to a prison from which escape was impossible. Among the residents, Katya suddenly recognizes Mikhail, her beloved who disappeared seven years ago. Soon afterward, a brutal murder occurs. Natalya Stepankova, whose husband died on this island a year ago, begins investigating the case, and Katya decides to help her.
