Восьмилетний Рома discovers an old rag doll in the attic, which unexpectedly comes to life and introduces itself as Капитан Чистюлькин. This new friend tells the boy about the terrifying Мусорный Монстр, which grows bigger every day because people neglect nature. Together, the heroes embark on a remarkable adventure to find a way to defeat the villain. Along the way, they learn simple ecological principles: how to sort waste properly, conserve water and electricity, and care for plants. Readers can join in the adventure by answering questions and helping the characters make important decisions. With the aid of magical spells, friendship, and knowledge of ecology, Рома and Капитан Чистюлькин not only conquer the Мусорный Монстр but also transform it into a kind ally of nature. The tale teaches children to love and protect the environment.