Scientist Professor Arnold Boyce, who was working on a project in Africa, had his lab destroyed by a local hostile tribe.
Informed by gameskeeper Dick Mason that the tribe in question, the Akari, worship a huge statue in the shape of an ape called Mytek, Boyce decides to build a solar powered robot the same size and shape as the statue in the hopes that it will convince the tribe to leave him and the tribe he lives among alone.
Things go awry when his dwarfish assistant Gogra steals the robot as soon as it's ready and uses it to try to turn the Akari into his own personal army so he can reek his vengeance on a world he hates
After much tribulation Boyce and Mason are able retake the giant robot ape, though Gogra escapes.
After that the pair, and the robot, face a series of giant monsters and robots, as well as the return of Gogra again and again.
At first a puppet controlled by Boyce, Mason or Gogra, eventually the professor installs a computer brain in Mytek making him capable of learning and acting independently, and as we know computers are never evil, things go swimmingly after that.