It’s not for nothing that they say: someone else’s soul is darkness. A sympathetic, trusting girl Nadya, a programmer by profession, accidentally meets a sweet old lady and becomes her friend. And suddenly Sofya Alexandrovna is attacked. Dying, she declares Nadya her heir and makes her promise to find out the killer. But inheritance turns out to be dangerous. Having received compromising materials on various people, Nadya learns that her elderly friend was... a blackmailer. To keep her promise, Nadya begins to unravel the secrets of these people. There are many secrets, people are different. But which of them is so cruel that he went, armed with a hammer, to watch for an old woman? And won't the same fate await Nadya?