Hellboy, his pyrokinetic girlfriend, Liz, and aquatic empath, Abe Sapien, face their biggest battle when an underworld elven prince plans to reclaim Earth for his magical kindred. Tired of living in the shadow of humans, Prince Nuada tries to awaken an ancient force of killing machines, the all-powerful Golden Army, to clear the way for fantasy creatures to roam free. Only Hellboy can stop the dark prince and prevent humanity's annihilation.

The Empire of Izmer is a divided land: elite magicians called “mages” rule while lowly commoners are powerless. When Empress Savina vows to bring equality and prosperity to her land, the evil mage Profion plots to depose her.