The Simian Senate convenes a secret session to discuss an event that could have direct effect on ape society - one of Urko's soldiers, returning from a journey into the Forbidden Zone, babbling about intelligent humans.

During an archeological dig on an ancient ruin, Cornelius uncovers an ancient, human-made book entitled 'A Day at the Zoo'. Needless to say, the images and words inside could lead to much trouble for man and ape alike....

Bill and Jeff discuss the best means of eluding Urko's troops that are pursuing them, and Judy, relentlessly.