There are three forces in this world: The Green, The Red, and The Rot. Each of these balanced forces have an avatar: Swamp Thing for the Green, Animal Man for the Red, and now, the evil Anton Arcane has become the avatar for the Rot.
Arcane wants more power for the Rot, so he is trying to upset the balance on Earth by battling against the Green and Red. Animal Man and Swamp Thing have tried to stop the Rot, but they end up in a future where the Rot has already won. The Green and Red have lost.
All of the DC Universe --- including heroes like Batman and Superman --- have been twisted in this Rot-filled future into very different creatures. While Buddy Baker (Animal Man) and Alec Holland (Swamp Thing) try to reverse things in the future, characters that are still in the present-day DC Universe work to prevent the seemingly inevitable triumph of the Rot over the DCU.