Green Lantern: True Colours (Graphic Novel) (DC Comics)

Green is the color of will power, and one of the most powerful lights in the universe. The Guardians have harnessed this power to create an intergalactic police force wielding green power rings. What happens when Hal Jordan and Kilowog find one of these rings abandoned in space? Has one of their comrades fallen, or is something even more sinister happening?