The forced union of three civilizations faces a new test - the development of the rich planet Ark, which is necessary for both people and aliens to survive. Will they be able to exist together peacefully on one planet, or will mutual contradictions break the alliance and lead to rivalry? Is everything so simple with the Ark itself, and where have the old owners of its ruins and mysterious dungeons gone? Will this planet be able to become for three intelligent races something more than just a new home? The answer will have to be sought by Ilya Anechkin, the first commander in history of a joint battalion of humans and aliens.