 Centuries into the future, the countries of the world have finally wiped out warfare, only for Earth to be laid waste by an impacting comet. The only survivors, intelligent androids, succeed in sending one of their kind back into the past, just as Earth is burnt up. He saves from a fatal car crash the inventor of several robotics patents, whose notions have been trashed and ignored, but which in several decades will be rediscovered and used as the basis of android development. Together, they must prevent the destruction of a space-exploration research lab, which caused the cut of space funding that allowed the comet to destroy Earth in the first place! And they must accomplish all this while being hunted by the scientist who investigated and killed the last android sent back from the future...