Merlin: Season 4, Episode 3

4 - 3: The Wicked Day

While the citadel of Camelot is frantic in preparation of the birthday party of Prince Arthur, King Odin plots to ensure this is one celebration Camelot will never forget. The prince's old adversary has arranged for a deadly assassin to lurk among the assembling guests with intent to strike. As a result, the kingdom is left devastated and it comes down to Merlin to set things right again. How far will he be prepared for order to be restored to Camelot? Will he really risk everything and reveal his secret?