Equilibrium: Beyond the clouds

Set 400 years in the future, after earth has been devastated by nuclear war, ancient evil forces have ruled the remaining creatures. These forces believe in upmost purity and are disgusted by hybrid creatures that run amok in the ruined world all around.
The opposites to the current forces have fled far away, and their location has been long unknown. That is, until four who wish to end the oppressive and evil rule, set out to find them.