en Cuevana 3. Valentin, a student at the Institute of Cinematography of St. Petersburg, will have to make a documentary film about Baikal as a diploma work. His friends remind him of Stepan, a former classmate from Ulan-Ude. He decides to turn to him for help. In Ulan-Ude, together with their friends, the guys get into various funny situations. For three days, they rest on Lake Baikal in the Chivyrkuisky Bay, help Valentin in the filming of a documentary and talk about all the beauties of the "sacred sea".