At the start of the first episode, a shady character arrived on earth via a comet, landing in Tokyo. He called reporter Tom Mura to arrange a meeting, but Mura?s son Miko answered the phone instead. The reporter thought the whole thing was a prank, but the next morning, the entire Mura household was transported to a strange jungle, where they first witnessed the mighty power of Rodak, an outer space creature bent on world domination. Miko snapped a picture of Rodak, which brought the boy to the attention of a giant robot named Goldar, the Space Avenger.
Goldar brought both boy and picture to Mount Olympian, the volcano home of Goldar, wife Silvar, and their creator, the outer space scientist Mathusem. The two robots were smitten with the young lad, and to complete their metallic family, they asked Mathusem to create a robo-child for them. The result was Gam, a robotic near-duplicate of Miko (although the real Miko didn?t have silver antennae). All three robots had the power to transform into sleek rocket jets, the better to fly into battle. Mathusem also gave Miko a whistle which he could use to summon the robotic protectors?one whistle for Gam, two for Silvar, three for Goldar.
Meanwhile, Rodak had unleashed upon the world the deadly force of Molesaurus, a subterranean monster. Goldar and family rocketed into action, battling the first of many gargantuan creatures. Rodak kept launching wave after wave of baddies, including the winged Birdaurus, the shapeshifting Lugo Men (who turned into a greenish goo when they were killed), the metallic Noronda, giant beetle Nardo, mini monster Lodi, and Kono, ?The Mightiest Creature of All? (really Rodak in an alternate form). Goldar, ever the noble robot, always tried to talk the monsters out of fighting, but when that failed (and thankfully, it always did), titans collided in elaborate battle scenes.