Dentist Maxim Krivtsov has an unusual hobby: he photographs Moscow metro stations late at night, when the last train leaves and there is not a soul in the subway. But in the printed photographs the shadows of men, women, children are clearly visible... Krivtsov is trying to find an explanation for this “mystical devilry”, turning to metro employees, phantomography specialists, and optical physicists. If he knew that by telling these people about his hobby, he will be an ideal candidate for murder charges! Fleeing from arrest, Maxim descends into the “underworld” - into the Moscow dungeons. Finding himself in one of the communities (and there are hundreds of them in the subway), Krivtsov meets a professional beggar, a pickpocket and a weird scientist. From them and other representatives of the “underground,” Maxim learns about the metro something that most of us, who spend several hours every day in the subway, are unaware of.