Synopsis: From the back cover of the DAW first edition: "Rewrite the sacred past - and revise the fateful future. When Astronaut Williamson returned after the longest flight ever made he found that the great civilization that had launched him was gone... destroyed in a chaos of its own creation. But somewheres in what had once been Michigan the Republic welcomed him back. The Republic that was a kingdom, the Republic that consisted of one underground city ruled by a weakling monarch and a power-hungry priesthood. Testament XXI is the story of the time of showdown, one hundred years after Doomsday, when men still yearned to learn the meaning of their continued existence, and when all that humanity had held sacred for two thousand years had been perverted to a continued drive for mortal ambitions."