One evening, young Mikko Mura receives a telephone call from an unknown man identifying himself as a messenger of Rodak, a conqueror from outer space. The caller tells Mikko that Rodak will take the boy, his mother Tomoko and his father Tom on an interesting journey at 6:00 AM the following day. The next morning, Mikko awakens and finds that his neighborhood has been transformed into a primitive jungle. A large dinosaur appears, and Mikko runs into the jungle to look for the unusual creature. The dinosaur sees him and begins to walk in his direction. Suddenly, Rodak’s saucer appears in the sky and destroys the creature with a special ray. Dropping from his ship, Rodak tells Mikko and Tom Mura— a reporter for United Press International— to print in the newspapers what they have just witnessed. Before Rodak flies off, Mikko takes a picture of him with his camera. With his house back in the old neighborhood again, Mikko has the photo developed. He then hears the loud roar of a jet engine, and looks outside to see a huge rocket land beside his house and immediately turn into a 50 foot tall golden robot. The giant introduces himself as “Goldar”, a friend to the people of Earth. Goldar asks Mikko for the picture. When Mikko refuses, the camera flies from his hands and into the giant palm of the Space Avenger! He tells Mikko that he must show the picture of Rodak to his creator, Mathusam, a scientist from outer space.