In an attempt to resist unscrupulous medieval witches and willing to use thousands of years of magic to reach his ultimate goal of destroying all of humanity, Hellboy arrives in the UK where he must defeat the consort Merlin and Regina Nimue. But the confrontation between good and evil turns into a very dangerous and bloody struggle, which not only risks generating a lot of collateral victims but can even provoke the end of the world – an outcome that Hellboy tries to avoid any price.