Commander Luke Graham is selected to lead the first manned mission to Mars. Upon setting foot on the red planet, the team discovers an ancient, domelike structure which appears to be a beacon. The dome destroys the team and leaves Luke injured. The recently widowed Jim McConnell leads the rescue mission. When they arrive, they find Luke surprisingly alive, and he has spent the time alone learning the secrets of the mysterious construct. The question now becomes: do they enter the dome and answer humanity's oldest question, perhaps risking their lives in doing so, or return to Earth with what they do know and return in force with equipment and supplies?