Walking along the embankment after work, Roman Tartalatov meets sectarian Lana. And although he is far from the sermons that the girl reads to him, he meets with her again and again, realizing that he has fallen in love. Relatives who are worried about Roman find out that the sectarians who preach during the day on the embankment at night transform into moths - some kind of fallen angels. But instead of turning Roman away from Lana, it makes him eager to help her. But this can only be done in one way - by penetrating the sect from the inside...