Another astronaut who has followed Taylor's trajectory has landed on the planet and he finds Nova (Linda Harrison) wandering around on horseback
The astronaut named Brent (James Franciscus) comes to "Ape City" as Nova leads him to Zira (Kim Hunter) and Cornelius, this time played by David Watson instead of Roddy McDowell.
Zire tends to a wound Brent has and then helps him out of the city. Brent and Nova are soon captured by a mysterious race of humans who live underground, have telepathic powers and worship a nuclear bomb known as a "doomsday bomb".
Brent and Nova are tortured by the humans and then Brent meets Taylor Charlton Heston), who has been a captive for a while. The two plot an escape at the very time the apes are marching into the "forbidden zone" to kill the humans.
All out war breaks out and the humans are killed along with Brent, Nova and Taylor, but Taylor lives long enough to set the bomb into motion and the entire planet is obliterated. Thus ends the second chapter of this franchise.
Despite what some say, this is a very good follow up to the original and the ending sets up the third installment. The rest of the cast includes Maurice Evans as Dr. Zaius, Paul Richards, Victor Buono, Jeff Corey, Natalie Trundy, Don Pedro Colley and James Gregory as the power mad gorilla named Ursus.