A teacher from a provincial university, Ksenia Petrovna, comes to St. Petersburg for three months to work on an article about autobiographical literature. But instead of quiet studies in the library, she finds herself taking part in unusual events and witnessing unexpected deaths. Are all these oddities and passions connected with the crypto diary of an unknown person that Ksenia and her young colleagues are trying to decipher? And what does the diary of a young girl from Totma, which was shown to Ksenia by a new acquaintance, have to do with all the incidents?