The mighty citadel is buzzing in anticipation of the prince's birthday celebrations. But Arthur's old adversary, Odin, promises to ensure this is one party Camelot will never forget. For amongst the assembling guests lurks a deadly assassin, set to strike.
Uther's heroic act saves his son's life, but leaves the king mortally wounded. Arthur seeks to save his father with magical help from a disguised Merlin, but Morgana intervenes and reverses the boy wizard's healing efforts, leaving Uther to perish and Arthur to at last take his place as king of Camelot.
As the dust settles, Camelot is left devastated. But just how far is Merlin prepared to go to put things right? Would he really risk everything and reveal his secret?
Listen to the Merlin star answer your questions from Facebook.
The Merlin star answers your questions from Facebook.