Luke, portrayed with energy by Jasen Fisher, resides with his grandmother Helga (May Zetterling) following the unexplained loss of his parents. She’s taught him about witches, making him watchful when he and Bruno, a new friend who is always looking for food (played by Charlie Potter), encounter Eva (Angelica Huston) at a hotel by the sea. After overhearing her wicked plan as she speaks to a gathering of older women,…