I bet you're confused about the Planet of the Apes series.

I bet that, like I used to be, you're more than a little confused about the whole Planet of the Apes series. Don't worry, I'll provide a quick guide.

1 - The Planet of the Apes
Charlton Heston goes through some time worm hole and lands on a barren planet he later discovers is earth. He is with two other astronauts, one who dies at the scene of the landing and one who is murdered. He is captured by apes and learns that apes are the dominant species on the planet and humans are slaves. He is cared for by two doctors, Cornelius and Zira, who eventually become his friends and assist him with his escape. He does some stuff that really angers the apes and is forced to run away into the "forbidden zone".

Here's the key: Dr. Zaius admits to Taylor that he knows man and ape's roles were reversed long long ago.