Doomsday tale suggested by a CD-ROM game called Gadget, by the author of Kalifornia (1993) and The 37th Mandala, published earlier this year. The reader is set down in the eighth year of the Empire, ruled by a ruthless Emperor who, besides old age, has one weakness: his lust for the heroine, young Elena Hausmann. Elena was befriended by the Emperor in early life, as was her brother, Louis, who has become a soldier and henchman for the Emperor. Elena, however, has become part of the resistance. Gradually, we learn that the Third Force referred to in the title is the intelligence behind the approach of a great comet, hurtling on a collision course toward Elena's planet; its harbingers include the inexplicable actions of certain characters presumably loyal to the Emperor, and the sudden appearance of a malevolent machine that dissolves personalities into something called xenium. Yet there is a benevolent aspect to the Third Force, too, as a path is prepared for Elena, her brother, and certain valued others to escape. Beautifully composed and full of high-level concepts (such as a virtual library and binoculars that allow one to look upon the future), but weighed down, in the end, by a plot that is strictly Buck Rogers.