Apprentice Adept is a heptalogy of fantasy and science fiction novels written by English American author Piers Anthony.
The series takes place on Phaze and Proton, two worlds occupying the same space in two different dimensional planes.
The first three books in the series follow Proton serf Stile as he enters Phaze and becomes an important political force there.
Finally, volume 7, Phaze Doubt follows Bane's and Mach's nine-year-old children, Flach and Nepe, among others.
Most of the atmosphere of the planet has been destroyed through the mining of Protonite, a valuable energy source, and the inhabitants of Proton live in domed cities with artificial life support.
In addition to the Citizens and serfs, Proton is home to advanced robots, some of which are self-aware and possess their own free will.
For instance, in the books, Stile plays a Naked/Arts round in interpretive dance, while later on the same category produces extemporaneous poetry.
The final winner of the Tourney is immediately made a Citizen and given a small percentage of the annual Protonite production equal to about one kilogram at the moment of Citizenship.
Other Tourney participants who last until the final rounds are rewarded by being allowed to stay a serf on Proton for an additional term of years.
Besides humans, it is also populated by several species common to the fantasy genre such as unicorns, werewolves, vampires, trolls, and animalheads—humans with beast-heads like the Minotaur or Anubis.
For instance, when one of Proton's self-willed robots crossed the curtain into Phaze, she became inert until returned to her home dimension.
Although the actual Oracle is hidden from sight for reasons explained later in the series, it is accessible through a speaking tube.
The Oracle is actually a computer with its source line running through the west pole so it can have power in Phaze.
The Game-champion serf Stile is assaulted on Proton by an unknown enemy, but learns he can escape into a mysterious fantasy world (Phaze).
Years of mining for the high-energy mineral "Protonite" has left an imbalance between Proton and its sister world, Phaze.
To restore the balance, Citizen/Adept Stile must juxtapose the frames and transfer "Phazeite" from Phaze to Proton, or the two worlds will both be destroyed.
However, he faces resistance from the Contrary Citizens and Adverse Adepts who stand to lose considerable power if he is successful.
Both fall in love with people from the other frame: Mach with Fleta, the daughter of Neysa the unicorn, and Bane with Agape, an amorphous alien.
Lysander, an alien mind in a human body, is sent to infiltrate the Phaze/Proton resistance but finds that a prophecy makes him the key player in the planet's defence, though his loyalty remains with the BEMs.
The realm of Phaze is also briefly visited in Piers Anthony's twenty-seventh Xanth book, Cube Route.