Masha has a rare feature - her thoughts and actions are pure from worldly greed and, in general, from any sin. This is imperceptible to others, but it is well known to demons and angels who begin to fight for the innocent soul of a Moscow schoolgirl. If the demons win, then Masha will become a servant of evil, possessing a rare power. She will forever change the balance in favor of the dark forces. If Masha turns to the angels, then her mission will be to fight evil on earth, to save human souls and human lives. Ahead of Masha are trials and temptations, sacrifices and benefits, hatred and love, and, in the end, the answer to the question: who is she really - an angel or a demon?