In 9th century China, a corrupt government wages war against a rebel army called the Flying Daggers. A romantic warrior breaks a beautiful rebel out of prison to help her rejoin her fellows, but things are not what they seem.

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.