The battle for Camelot is about to begin Swords, sorcery and swashbuckling adventure return in this third season of the hit series, following our heroes Merlin and Arthur as they face their greatest challenge yet. When misbegotten secrets are exposed and old friends choose new sides, they soon discover that the great battle for Camelot is only just beginning. . . with epic action sequences, stunning CGI sequences, terrifying new monsters and a guest cast featuring Warwick Davies (The Harry Potter Series , The Chronicles Of Narnia); Miriam Margolyes (The Harry Potter Series, Being Julia); Mark Williams (The Harry Potter Series, The Fast Show); as well as Emilia Fox (Ballet Shoes, The Pianist) returning as Morgause and Santiago Cabrera (Heroes, Che) as Lancelot, the third series of Merlin will be bigger, bolder and more action-packed than ever.