Superman matches wits with an evil mastermind and a computer genius who discovers the one substance that can harm the Man of Steel. Combining the known ingredients of Kryptonite with a guess at the unknown, the genius invents a new Kryptonite that doesn't kill Superman--it turns him evil. Meanwhile, a giant computer has been built for the mastermind that becomes self-aware and cannot be shut off. This entertaining combination of spectacular special effects and irrepressible comedy, once again directed by Richard Lester, features terrific madcap turns by Richard Pryor, Robert Vaughn, and Annette O'Toole and yet another majestic score by John Williams.