On Sllth, a deadly plague has been progressively destroying all life. Their only hope is to emigrate to another world. Earth [Zapff to Sllthians] is close enough, but it is currently unsuitable. Sllthians, however, have a way of changing this. They can manipulate time. Meanwhile, Douglas Nietzsche, a professor of American history, has immersed himself in alcohol and "speculative history" in an attempt to obliterate his anguish over a lost love. Thoroughly unheralded, his four controversial articles concern how tragic American history might have been, had it not been for certain key events and heroic individuals. One of his students, an exotic woman, has developed an unusual interest in these writings. They have been selected as working plans for the Sllthian mission. When an unforeseen problem provides a difficult obstacle for the mission's success, Nietzsche's aid is enlisted.