Terror strikes an international exposition, showcasing giant robots from around the world, when it is suddenly attacked by the mysterious Iron Alliance, who seizes all of the nations' automatons. But Dr. Deviler, a mad despot who plots to overthrow mankind, fails to capture Red Baron, a super robot built by Kenichiro Kurenai. When Kenichiro is captured, he entrusts Red Baron to his younger brother, Ken, a member of the S.S.I. (Secret Science Investigation) organisation. Now, Ken pilots Red Baron to fight against the Iron Alliance's mechanical hordes to protect the future of the human race!