Arthur embarks on a solitary quest to retrieve the Golden Trident from the Fisher King and prove himself worthy of the Camelot throne. With the Prince beyond the protection of the citadel, Morgana sees an opportunity to use her dark magic and gives him a precious bracelet containing a Phoenix Eye. She insists he wears it at all times for protection, but it saps him of his life force and he is left defenceless in the Fisher King's perilous realm. With the help of Gwaine, can Merlin reach him in time and fulfil his own quest to protect the future king of Camelot?

Morgana is tormented by dreams of Guinevere becoming Queen of Camelot. Encouraged by Morgause, she decides to reveal Arthur and Gwen's courtship to Uther, who will do whatever it takes to stop his son from marrying a serving girl.