The film begins with a flashback to the Middle Ages, where the Blood Queen Nimue, a powerful witch, is defeated by King Arthur. Her body is dismembered and scattered to prevent her resurrection. Centuries later, Hellboyβa demon from Hell who fights to protect humanityβis dispatched by the Bureau for Paranormal Research and Defense (B.P.R.D.) to investigate supernatural threats.
During a mission, Hellboy uncovers the plot of Gruagach, a vengeful supernatural being, who seeks to resurrect Nimue to exact revenge on humanity. Nimue, once resurrected, plans to unleash hell on Earth and attempts to lure Hellboy to her side, revealing his destined role as the harbinger of the apocalypse.
Torn between his demonic nature and his duty to protect humanity, Hellboy teams up with Alice Monaghan, a psychic, and Ben Daimio, a shape-shifting agent. Together, they face numerous adversaries, including giants and mythical creatures. In the climactic battle, Hellboy confronts Nimue to stop her from initiating the apocalypse, while grappling with the truth of his origin and destiny.
In the end, Hellboy rejects Nimueβs offer to become the “Destroyer of Worlds” and kills her, restoring balance to the world. The film concludes with Hellboy embracing his true self and continuing his fight for humanity alongside his trusted allies.