The third -and unexpected,considering the ending of the second part-sequel of the apes saga is probably the best of the four, thanks to Kim Hunter's and Roddy McDowall's characters Zira and Cornelius,who play a prominent part here. Here ,Pierre Boulle is more present than in "beneath the planet..":the reason can be found ,I think, in the Baby,the menace for the human race. In Pierre Boulle's book,Ulysse Mérou(Taylor) and Nova have a baby,and that's why they cannot continue to live peacefully with the simian race;had Cornelius and Zira not intervened,the trio would have been slain ruthlessly.Thanks to them,they can escape from the planet and go back to earth where they.... (No,I won't tell you anything more,please,read the book!) Here,it's the same situation ,a monkey baby instead of a human one.And the humans act like the monkeys in the book.There's a good original idea in the screenplay :the using of a circus as a place to hide .Taylor should have thought(should think!) of this when he was (or is!)in the apes society.