Morgana leads a terrifying manhunt in pursuit of her old foe Alator of the Catha, for she knows without doubt that he can tell her exactly where to find Emrys. Merlin's life is in severe danger, so when the mysterious Finna offers to help him, is he right to trust her?

Cast: John Hurt, Gary Lewis, Katie McGrath, Bradley James, Angel Coulby, Colin Morgan, Rupert Young, Eoin Macken, Richard Wilson, Barry Aird, Sorcha Cusack, Alexander Vlahos, Tom Hopper