Superman’s increasing hold over the Earth has concerned the Guardians of the Universe. And with Hal Jordan believing in Superman’s world vision, his allegiance to the Green Lantern Corps is being tested. So under the direction of the Guardians, two more Lanterns – Guy Gardner and John Stewart – are sent on a diplomatic mission to Earth to see the effect of Superman’s rule.
— Description from Comic Vine community (comicvine.gamespot.com).
