Olga Barkovskaya comes to the defense of her friend, Daria Novikova, who is accused of murdering her husband Anton. But she will be able to find the real killer only by deciphering the message that Anton hid in the text of his book using the Caesar cipher. Olga finds the keys to solving the cipher in the Novikov family history. Revealing the unsightly secrets from Anton's past one by one, Olga gradually gets closer to the most terrible secret that caused Anton's death.
