Centuries ago, a supernatural champion named Master Gregory (Jeff Bridges) defeated Mother Malkin (Julianne Moore), a malevolent witch. Now, she has escaped imprisonment and thirsts for vengeance. She summons her followers and prepares to unleash her wrath on humanity.
Only one thing stands in her way: Master Gregory. Gregory takes Tom Ward (Ben Barnes) as his new apprentice, but he has only until the next full moon to teach Tom what usually takes years: how to prevail against dark magic.