In the distant city of Blagoveshchensk, a father and his two sons, Rodka and Kostya, live together. After graduating from college, Kostya works as a surgeon and suffocates from the "greyness" of others, and 15-year-old Rodka suffers from the inability to help people. One day, a young woman appears in their house, whom Kostya brings.

The Soviet boys, Vadik and Yura, together with the mischievous little girl Tosha, are children with a kind heart and good life philosophy. One day they find money on the street, which must be returned to the owner without fail. But where to find an inattentive citizen who has lost not only money, but also a booklet with quite important information. So, begins the time of exciting adventures, breathtaking moments, high-quality humor and instructive-entertaining ideological line.

In the Crimea, on the shore of the Black Sea lives a girl nicknamed Dubravka. The girl plays soccer, swims in the sea, runs with boys in a race and often becomes a participant of any adventure. But the time comes - and Dubravka begins to grow up. She is as if in a “suspended” state: she is no longer interested in playing with boys, and older boys and girls do not pay much attention to her or perceive her as a child. In the house Dubravka settles vacationer Valentina Grigorievna. The girl likes her so much that Dubravka even “fell in love” with her. Dubravka's neighbor, the lonely father Peter Petrovich, and Valentina sympathize with each other, and Dubravka becomes very jealous of her. The girl does not know where to go from the contradictions simmering in her.