Superman saves Metropolis from Lex Luthor's giant missile, but inadvertently frees three Kryptonian criminals, who immediately head for Earth.Superman saves Metropolis from Lex Luthor's giant missile, but inadvertently frees three Kryptonian criminals, who immediately head for Earth.Superman saves Metropolis from Lex Luthor's giant missile, but inadvertently frees three Kryptonian criminals, who immediately head for Earth.