Burke (solid James Naughton) and Virdon (the equally sturdy Ron Harper) help the determined Leuric (nicely played by Frank Aletter) build a hang glider. However, Burke and Virdon are unaware that charming chimp scientist Carsia (a strong and credible performance by Joanna Barnes) plans to use the flying machine for her own deadly reason. Director John Meredith Lucas relates the absorbing story at a steady pace and stages some exciting action with flair. Galen (Roddy McDowall in customary fine form) has a few amusing scenes in which he gets wooed by Carsia. The smart script by S. Bar-David and Arthur Browne Jr. provides interesting insights into the shrewd cerebral methods of the chimpanzees versus the more brutish physical ways of the gorillas. The plot takes on a truly disturbing dark tone when Carsia's true intentions are revealed. Moreover, the sound acting by the capable cast keeps everything on track: Martin E. Brooks as the gruff Konag, Mark Lenard as the ever-angry Urko, and Booth Colman as the sage Zaius. A worthy closer to this cool series.