An assassin comes to Camalot among entertainers gathered for Arthur's birthday celebration. Though the prince is the target, it's Uther who sustains a mortal wound while dispatching his son's would-be killer. As the unconscious king lies on his deathbed, Arthur, in desperation, decides to turn to magic for help. Seeing this as an opportunity to end the Pendragon purge against wizards, Merlin, in his guise as the aged Emrys, agrees to restore Uther, but Agravaine, knowing Arthur's plan, gets a charm from Morgana to hang around Uther's neck that will reverse any magical efforts to make him well.
—statmanjeff