Bill and Jeff know that the humanoids must be moved to a safer place for protection from Urko and his army. Their one hope is to ask Zira and Cornelius for help in finding a more secure location for themselves and the humans. They secretly hitch a ride into the city on an ape farmer's truck. Meanwhile, Urko reviews his plans for a blistering attack on the humans and orders his aides to search for Blue Eyes. In six days, they will strike. The general hopes to calm Zaius' anger over losing Blue Eyes by capturing all the humans. As night falls, the two men sneak into the city and cross the river in an abandoned boat. A gorilla patrol boat almost spots them, but they are able to reach the shore unseen. While soldiers sweep the area in search of them, the men proceed down a drain pipe into the heart of the city. Barely escaping a giant spider, they emerge from the pipe close to the lab. Inside, Zira is worried that Zaius suspects them of aiding Bill and the humans, but Cornelius argues that Zaius has no proof of their actions. Suddenly, Bill and Jeff come through the window. Bill thanks them for helping him escape earlier and asks Cornelius to help them find a safer place for the humans. Cornelius feels it is disloyal to his country to help, but after Bill points out that humans are no different than any other endangered species, Cornelius suggests a valley which lies to the south of his latest digging site. He has never seen it, but knows of its existence from an old map in the Simian National Library. He promises to make a copy of the map and take them to the general area. Suddenly, a knock is heard on the door. As the men hide, Dr. Zaius comes into the room. He asks Cornelius for a detailed report on Blue Eyes' behavior which may help in locating him and the humans. When Zaius leaves, Cornelius reluctantly agrees to proceed with their plans. The men spend the night in the lab.
The next day, the group travels to one of Cornelius' digging sites ninety miles from the valley and fifteen miles from the humanoids' caves. The valley can be reached by either traveling the heavily patrolled mountain roads or the unexplored underground river. Having been almost spotted by a gorilla patrol, the group decides the river is their only hope. Bill and Jeff take the map, bid Zira and Cornelius farewell and head for the underground river. They float past the wreckage of a once great human civilization. Suddenly, a waterfall current begins pulling them nearer the edge. The walls are too smooth to hold and they plummet over. Later, they are revived by humans; they have reached the humanoid caves. Figuring that their ship's laser could come in handy when they reach New Valley (as they have named it), they decide to return to the ship to try and retrieve it. Back at the lab, Zaius is pressing Zira for the report he wants, so she tells him that Cornelius is finishing the document in the solitude of his excavation site. Urko, however, is suspicious of Cornelius' actions and alerts his troops that Blue Eyes may be nearby.