Talented IT specialist Mark Ozerov checks companies' defense systems against hacker attacks. After completing one of the tasks, he receives an email asking for help in understanding the suicide of a certain Marina Zaitseva. Allegedly, very valuable information was transferred from her email to competitors, after which the girl was fired from her job, fell into depression and, as a result, took her own life. Mark agrees to help. During the investigation, he gets the feeling that some of the tragic events of the last days of Marina’s life were specially staged. At the same time, Mark realizes that he is being dragged into other people's dirty deeds, and decides to leave the game, as it seems to him, forever. But this story is just beginning. A few days later, a killer breaks into Mark's house...