Eight-year-old Nina is an impulsive and emotional girl, quickly igniting ideas and dropping them halfway. Nina would probably have abandoned her new hobby - music - too, but a strange thing happened: the instrument began to behave defiantly, play by itself and provoke the hostess in every possible way. And soon Nina was completely kidnapped along with him. The villains plan to subjugate the world with the help of the piano.
Petersburg was swept by a wave of an unusual cultural movement: an unknown enthusiast organizes art events, trying to draw attention to forgotten monuments. This enthusiast is Mitya. He is 18. And he keeps a vow of silence. In the world of Mitya's ideas, everything is harmonious and understandable exactly until the energetic trickster Kowalski joins him with his girlfriend, the charming but dependent on him Polina. With new friends, the movement is rapidly gaining momentum: and now young people are already launching an ambitious campaign to save the old greenhouse building from demolition. But the further, the more complex the intertwining relationship within the trinity. And the spark that flared up between Mitya and Polina intensifies the already insoluble ideological dispute between the guys. When the rally on the day of the demolition finally gets out of control, Mitya will have to finally decide what is more important for him - people or monuments.
