The Moon, orbiting the Earth for thousands of years, is an artificial satellite built by the Creators, a highly developed race of space vagabonds using planets as industrial bases or incubators to grow biological organisms of a wide variety of species. A long time ago, such an incubator existed on Earth. But something did not suit the Owners, and they left this sector of the Galaxy forever, leaving the biorgs that had bred on the planet and the ownerless station hanging over their heads unattended, considering it unnecessary to destroy absolutely everything. Russian cosmonaut Semyon Lisitsyn will have to find out about this by visiting the bowels of the Moon, the ships of the Creators and other planets.