Arthur meditates on a quest he must undertake to win the throne of Camelot: To venture to the Perilous Lands and retrieve the Golden Trident from the Fisher King. Gaius enlightens Merlin on the Fisher King: A man of legend, said to have been mortally injured hundreds of years ago, but kept alive by powerful magic.
Meanwhile, Morgana is shopping with Gwen when an old woman clasps her hand. The King's ward looks closer and realizes it is her sister. Morgana slips away to tell Morgause of Arthur's quest. Seeing a chance to end Arthur, Morgause gives Morgana the Phoenix Eye, a bracelet that saps the wearer of life force.
Morgana wastes little time in getting the Phoenix Eye to Arthur, who is touched and proudly wears the bracelet as he departs from Camelot. Merlin is drawn to its power and is alarmed to realize it is a gift from Morgana. He and Gaius frantically search through books and identify the artifact. Merlin resolves to follow Arthur, but Gaius tells him he will need help to cross the Perilous Lands.
Arthur is awoken in his camp by bandits, and a ferocious attack ensues. Arthur shows signs of fatigue and the fight is tough, but even a weakened prince is more than a match for a few bandits. He continues his journey.
Merlin enters a tavern just in time to see a brawl with Gwaine at its center. The pair steal horses and flee. Merlin is happy to be back in the company of the enigmatic traveller and tells him all about the danger the Prince is in.
As Merlin and Gwaine arrive at the dying embers of a campfire, they see Grettir, a dwarf who had earlier confronted Arthur. He tells Merlin that, in order for the Perilous Lands to return to their former glory, he must do as the Fisher King asks. Gwaine moves off and Merlin is about to follow, but Grettir stops him and says he must not deny the Fisher King's request, no matter what it is.
Arthur continues his journey and approaches an ominous-looking tower. As he gets closer, wyverns attack. The Prince swings his sword for all his worth, but he is weak – the Phoenix Eye burns brightly. Merlin and Gwaine can see the dark tower in the distance and the wyverns circling above. The Prince is clearly in danger.
Merlin bursts into the tower just as the wyverns are ready to devour Arthur. He calls out in the Dragon tongue, unsure if they will respond, but the wyverns fly over his head and out the door. Merlin rushes to Arthur's side and tears the Phoenix Eye from his wrist. Suddenly, a wyvern reappears and flies straight at them, but Gwaine's sword flies through the air, killing it.
The trio look for the Golden Trident. Merlin sees what looks like a throne room. He steps inside just as Gwaine steps on a booby-trapped stone. A heavy door separates Merlin from Gwaine and Arthur.
The Fisher King, who is seated on a dusty throne, offers Merlin a vial of water from the Lake of Avalon in exchange for the Phoenix Eye. Merlin wonders what he is to do with the vial, and the Fisher King tells him that in his greatest hour of need it will show him the way. Merlin, more confused than ever, takes the vial and hands over the Phoenix Eye. The Fisher King takes it and disappears.
The door to the throne room opens. The Prince is overjoyed to spot the Golden Trident on the throne and eager to get back home. Uther is proud of Arthur for returning with the Golden Trident. Merlin, on the other hand, is concerned about the Fisher King's warning.
Morgana and Mordred prepare to destroy Camelot (and Morgana plots to destroy Emrys). Is Merlin Camelot€™s last hope?
Merlin star Colin Morgan talks about the important events from episode 511 'The Drawing of the Dark.'
Mordred battles between his duty to his friends and that to his love, but is spared the choice.