A young teacher from the outskirts of Svetlana, having come to a seminar in St. Petersburg, gets acquainted with oil geologist Fyodor, who falls in love with a naive provincial woman. He throws an expedition, makes a proposal to the girl and arranges their cozy family nest. It would seem that life could be a continuous "day of happiness", but the luxury mansion eventually turns into a golden cage for Svetlana. Once walking through St. Petersburg, she meets an intelligent ambulance doctor, Berezkin. In love with his hometown and fascinated by history, he turns their joint travels on Peter into fascinating excursions. A sincere feeling gradually breaks out between young people.