A mysterious artifact of an ancient alien civilization, controlled by an artificial superintelligence that calls itself Gaia. A “prison world” inhabited by representatives of DOZENS of humanoid and non-humanoid “alien” races. A world in which the captain of the terrestrial starship Sirocco and his crew find themselves captive .But... WHAT IS this Wheel?! What does Gaia want from the captives who involuntarily master it?! And what are the goals of those who left this strange artifact?! Fans of “The Ring World” by L. Niven and “Heechie” by F. Paul !Read John Varley's classic trilogy!