The Adversary — Julian May

In the final novel of the award-winning sci-fi saga, both humans and aliens face destruction as a new time-portal opens a path back to the twenty-second century.

Human time-travelers from the sophisticated Galactic Milieu of the twenty-second century came to the Pliocene Epoch seeking a Garden of Eden. What they found was slavery under the knightly Tanu race, who had been exiled to Earth from a far galaxy. Freed by the usurper Aiken Drum, the humans enjoy a brief period of dominance. But now King Aiken's rule is threatened by the dwarfish Firvulag, who scheme to destroy both humans and Tanu in an ultimate Gotterdammerung.

This menace becomes almost incidental when Aiken discovers that his realm is about to be invaded by another human who possesses psychic powers even greater than his own. Marc Remillard, the instigator of the Metapsychic Rebellion, nearly conquered the Galactic Milieu before escaping through the time-portal after his defeat. Marc and his followers are out to overthrow Aiken just as a new time-gate is about to be built -- one that will provide a two-way portal between the Many-Colored Land and the future world of the Milieu.

The Adversary brings Julian May's Locus Award-winning series -- which also includes The Many-Colored Land, The Golden Tore, and The Nonborn King -- to a rousing climax.