Supergirl and Mary Marvel attempt to stop Sargon the Sorcerer's plot to turn The Man of Steel evil. Invading his spacecraft, the girls take a beating, until Kara's lucky decision to push the "big red button"(why do they always install 'the big red button'?) blows up the ship...letting teeny-bopper Mary put some moves on the now-sane Superman..Classic stuff from 1979.
Source: blog