A comet hits Earth. Billions die. Traumatized Earth builds a colony on the Moon. Seventy years have passed. But problems remain, and they are compounded with new ones for the space people who are sent to ensure the survival of mankind. Hard times on Earth have created new threats to their freedom.

The space people find, to their dismay, that its loss to others is their loss as well.

Boris Levsky, and his friends on the Moon, comfortable with the manifold blessings of freedom, and reluctant to sacrifice them in crisis, are eventually moved to its defense. But that fight inflicts painful losses - the struggle's bitter fruit. They find that there are always those among them who would restrict it. They learn that freedom does not defend itself. It is a distressingly repetitive story, but it is true.