By following clues given in Interstel announcements and through contact with alien races in space, the crew discovers an Old Empire starship adrift in space. An endlessly repeating distress call has been transmitting from the ship for over a thousand years. Before the fall of the Old Empire, a scientific expedition known as the "Noah 9" left Earth in search of Heaven, a paradise world to which humans could immigrate. The expedition never arrived, leaving a fleet of Mechan ships forever waiting for their arrival. Once their coded questions are answered correctly, the Mechans assume that the crew is, in fact, the long-awaited "Noah 9". Further investigation leads the crew to Earth, the home world of the Old Empire. The planet lies in ruins and is devoid of all life, but contains information about the history of Old Empire and its fate.