Olya could not sleep. My friend Katya was sleeping, and the entire sanatorium where they were vacationing was sleeping. The clock struck two in the morning. At that moment, a strange sound was heard from the next room... It seemed that someone had entered through the window! Dying from fear, the girl opened the door... and saw a man sneaking along the wall. Near the tiled stove, he began to tap the wall, then took out a knife and made a cut in the wallpaper. For a moment the villain raised his head and, seeing Olya, jumped out the window. What was the suspicious guy looking for? There is some secret hidden behind this! – the girl realized and rushed to wake up her friend...