About the book: 2021 / Nowadays, bandits are hunting for Professor Kashinsky and his invention. In the distant future, a lieutenant of the Time Security Service goes in search of an alien saboteur who has entered time space with the aim of destroying the Earth. By the will of fate, and also thanks to the changes that occurred in the time channel, Professor Kashinsky, the former marine Oleg Voronov who came to his aid, and a lieutenant from the future find themselves in an amazing parallel world of the times of Rurik. Time travelers, with the help of the hero Druzhina and the forest creature Leshko, will have to fight against numerous invaders of Slavic lands, witchcraft power and evil emanating from an alien monster who has donned the guise of the evil genius of Russian fairy tales, Koshchei the Immortal..