Academician Donnikov, the creator of the Health Reserve, where celebrities and politicians are treated, died in a car accident, leaving his daughter Masha an orphan. A month later, a dove brings a strange letter to their chapel. It says that the academician's death is not an accident, but a murder, and Masha must find a reliable person for a secret investigation.Masha turns to the detective Alexei Kisanov. He does not believe in mysticism, considering the "pigeon letter" a cruel hoax, but nevertheless takes up the matter out of sympathy for the girl. He is helped by an assistant Igor, in whom Masha causes more than simple sympathy ... A conversation with relatives of the academician unexpectedly lifts the veil over the unsightly secrets of the "Reserve". It seems that Donnikov became a victim of the intrigues of his high-ranking patients... The investigation is taking a dangerous turn: now someone is making an attempt on Masha's life. Who? Who needs the death of an academician and his daughter?!