Dmitry inherits from his uncle a luxurious mansion in Beloostrov, a suburb of St. Petersburg. The only condition for entering into an inheritance is to spend 24 hours alone in the inherited house, in complete isolation. The house closes automatically when you enter, blocking any communication with the outside world. Attempts to leave the house previously are recognized as a refusal of the will. While exploring the house, the young man finds a diary of an unknown person, which describes murders that occurred under mysterious circumstances within the walls of this mansion 20 years ago. In the remaining time, Dmitry needs to find out what really happened here and how his uncle is connected with it.