null: Superman is the target of yet another of Lex Luthor's evil schemes. Lex Luthor transforms terrorist John Corben into Metallo (recurring guest star voice Malcolm McDowell), a flesh and metal Kryptonite-hearted cyborg with evil intent and no emotions. Metallo's only mission is to destroy Superman. But once he discovers that he is more machine than man, Metallo attacks his creator and Superman must save Luthor from his own invention.