Planet of the Apes: Rule was an advertised follow-up novel to Planet of the Apes: Force and Planet of the Apes: Resistance (both written by John Whitman), but poor sales forced it's cancellation. It was written by J.E. Bright (not Whitman, as advertised) and would have been published by HarperEntertainment as part of their on-going series of Planet of the Apes spin-off novels.
The various human clans began to coalesce under the leadership of Sarai, and developed a highly organised city hidden from the eyes of the ape authorities. However, a visit by an incredulous Ari led Attar to discover it's location, and a brutal crushing of the human population followed, with Thade killing Sarai and most of her community.
- Rule was given the code ISBN: 006008376X, to be published by HarperEntertainment in June 2002 - "For the first time in their memory, humans have a chance to create a real civilization on the planet ruled by apes. But as the human factor gets stronger, new tensions between them and the apes fester."
- The story would have continued in a planned follow-up novel Planet of the Apes: Extinction.