Exploring the vast expanse of the universe for knowledge, humanity stumbles upon three immense trucks and a colossal spacecraft left behind by an extinct alien race on the planet Solo. Amidst their excavation efforts, the Buff Clan, a humanoid alien species, descends upon Solo led by Karala Ajiba, the daughter of their military commander, who defies orders to explore the planet. In pursuit of Karala, the Buff Clan ruthlessly attacks and razes the Earth settlement. To defend themselves, the humans—Cosmo Yuuki, Kasha Imhof, and Bes Jordan—enter the trucks, which combine to unleash the formidable giant robot known as Ideon. As they clash with their adversaries, the remaining survivors board the Solo Ship and escape, while the Buff Clan relentlessly pursues Ideon and its enigmatic power source.