When Cambridge student Huelo Topui of Tonga approaches linguistic anthropology professor Duke Pennington for help, the world-weary academic has no idea that the youth before him is the reincarnated soul of original human Adam. Huelo asks Duke to help him get information to find his long lost wife. The professor eventually succumbs to Huelo's preternatural charisma, and learns that Huelo is reincarnated, on a mission to find his reincarnated wife.
The skeptical professor can't help but want to know more about this enigmatic young man with fluency in every known language, both attested and unattested. Having lost two sons, a wife and a girlfriend, Duke had been suffering in silence for years, and now before him a young man with stories and knowledge that drew him away from his stagnant life of misery. Additionally, Duke felt a natural desire to assume a paternal role on their journey, which eased his guarded pain.
Huelo confides to Duke that he and his wife are Adam and Eve, and that they have been hunted and killed by an ancient tribe of mystic men called the Rodef throughout the centuries. As they travel through Europe, finding artifacts and clues to the Rodef's knowledge bank and traditions, Duke stumbles upon an enormous secret on his own. He learns that if Adam and Eve physically reconnect, Creation will reboot itself, wiping out the present human existence in the process. Huelo had been keeping this bombshell from the professor, waiting for the right time to explain. At first repulsed by Huelo's trickery, Duke is eventually won over by Huelo's powerful explanation that in the new Creation, no one will ever experience pain, disease or death again; he and Eve will get it right next time, not falling for the Devil's offer of false wisdom.
Duke and Huelo also discover the reason the Rodef had always been able to locate Adam and Eve with such precision: they struck a deal with the Devil who could sense their location whenever the primordial pair used their psychic powers, an energy circuit they share to employ powers of brief mind control and minor weather disturbances when needed. The Rodef were thereby able to rid the earth of a "parousia", an unnatural presence that shouldn't be tolerated. The Devil, in turn, was able to continue his domination of the degenerate world with his rule -- a lease over Creation that would end in the reboot.
In the climactic battle when Adam and Eve fight their way through an army of Rodef and a shape-shifting Devil, Duke learns that Huelo was once his son, the infant he lost moments after childbirth twenty years ago. The physical reunion of Adam and Eve, with Duke in their midst, results in a stunning rebirth of the world, and as the humanoid shapes of a man and a woman rise from the primordial muck, it is apparent that Eve is pregnant, presumably with a reincarnated Duke.