Jekyll and Hyde - Season 1 Episode 5

After curing Maggie, Robert learns that there is a distant branch of his family, the Jezequiels, living in an isolated house in Suffolk and, with Max in tow, decides to visit, learning from locals about a monstrous black dog which terrorizes the area. Robert is mistrustful of the widowed Renata Jezequiel, whose husband was apparently killed by the creature and whose student son Brant has disappeared. He believes she is a shape shifter working for Tenebrae who transforms herself into the black dog. He must use his own powers of alteration to expose the family's secret and defeat the monstrous canine – though victory comes at a cost.