A beautiful seventeen-year-old Małgorzata, a daughter of a poor widow, lives in a small village among the lakes. She is raised up in a catholic family and her main duty is to tend the cattle. One day when the girl takes a bath in the river a stranger appears out of nowhere. The man gradually gains the girl's trust. Under the pretext of anatomy studies, he directs girl's interest towards the secrets of human body. Małgorzata first poses for a portrait, than she begins to forget her shyness and poses for an act and eventually she becomes man's lover.