Merlin and Arthur are chased through the forest by a group of bandits. Much to Merlin's dismay, Arthur decides to take refuge in the Valley of the Fallen Kings. Arthur and Merlin do all they can to outrun the bandits, venturing deeper, when suddenly Arthur goes down. Merlin looks over in horror to see his friend bleeding heavily, an arrow protruding from his back.
Merlin incants spell after spell in an attempt to cure his friend, but his magic will not hold. The young warlock is at the end of his tether. Suddenly, a voice rings out behind him: Do not waste your tears, for the time for Arthur to die is not yet upon us. Merlin looks on as a wizened man, Taliesin, uses his own magic to treat the Prince. He then bids that Merlin follow him. Merlin stands in wide-eyed amazement as they reach their destination. Taliesin has brought him to the place where magic began: the Crystal Cave.
Suddenly, Merlin begins to see flashes in the facets of the rocks. Taliesin encourages Merlin to stare into the rocks around him, for they will reveal the future. Merlin watches carefully as several images reveal themselves to him: Morgana grappling with a horse, a woman holding a jewel-encrusted dagger, a dark hooded figure moving down a ghostly corridor, blood dripping from a hand, a raging fire...but it is the final image makes his eyes bulge with terror: he sees Uther asleep in his bed as the distinctive dagger is held above his head. He looks up to see the person holding the knife is the Lady Morgana. Merlin breaks out of his trance to find that Taliesin has disappeared.
Merlin resolves to do his best to put his visions from his mind. The following day however, his concerns return when Arthur informs his servant that his birthday present for Morgana is to be a dagger. This is promptly followed by the sight of the King's Ward in the Main Square struggling with a horse - the first image in the crystals.
But it seems his mind is playing tricks, for when Arthur shows Merlin the dagger he has chosen, it couldn't be more different from the one in his visions. Feeling somewhat reassured, Merlin quips to the prince that women like pretty things, not daggers.
Later that evening, Morgana's birthday banquet is in full swing. Merlin looks on as Morgana unwraps her gift from Arthur - the knife is beautifully jewel-encrusted and this is the second vision from the cave. Merlin paces the room as he talks to Gaius. He feels he was shown the images for a reason - they must not let Morgana kill the King. Gaius wants to know how he proposes to stop her. Merlin resolves to watch the King's ward night and day.
Later, Merlin follows as Morgana slips out of her chambers. As the King's Ward moves down the corridor, the moonlight lights her path; the third image from the crystals. The young warlock's eyes flash and the huge doors at the end of the corridor slam shut, blocking Morgana's path. But then, something unexpected happens, as the force of the door shutting topples a brazier, causing Morgana to lose her footing and fall.
Morgana is rushed into Gaius' chambers. The old physician does what he can to help, but his prognosis is not good and he is forced to admit her wounds are fatal. Uther is desperate; he tells Gaius that he must do everything he can to save Morgana, because she is his daughter.
The young warlock's guilt is compounded as he walks the corridors of the citadel. He summons the Great Dragon, desperate for a way to save Morgana. Having received it, he races back to Camelot and utters the Great Dragon's incantation over the unconscious Morgana. Almost instantly, she starts to stir. Camelot is overjoyed at the news of Morgana's recovery. Gaius, however, is more cautious. He knows that Merlin is responsible, and warns that he is playing with things that are beyond him.
That night, a cloaked figure slips into the citadel: it is Morgause. Morgana has news for her sister - she is Uther's daughter. Morgause is stunned, but delighted, as this means Morgana has a legitimate claim to the throne. Morgana, on the other hand, only wants vengeance on the father who has disowned her.
Merlin gets to Morgana's chambers just as she is preparing to leave, dagger in hand. The young warlock appeals to his old friend. Morgana tries to push him aside, but Merlin stands firm. The pair wrestle, and Morgana's eyes flash in anger. Merlin is hurled across the room. Behind him, the candles flare, catching the curtains alight. Merlin comes to, surrounded by flames - the next image he saw in the crystals. He jumps to his feet and heads off after Morgana.
The young warlock arrives at Uther's chambers to see Morgana standing over Uther, jewel encrusted dagger in hand - the final image from the Crystal Cave. Merlin's eyes flash, and a window flies open. A magical wind spins Morgana off her feet, sending her across the room. Uther wakes at the sudden noise and sees Morgana slumped against the wall. Thinking as quickly as she can, she tells the King that she was scared of the fire and just wanted to be near him. Merlin looks on, aghast, as Uther takes her into his arms.
Merlin's visions have now all played out. However, Gaius warns that events may have taken a turn for the worse. He fears Morgana knows the truth of her lineage. If this is so, then Arthur will need to be careful, for he is the only thing standing between Morgana and the crown.
Morgana and Mordred prepare to destroy Camelot (and Morgana plots to destroy Emrys). Is Merlin Camelot€™s last hope?
Mordred battles between his duty to his friends and that to his love, but is spared the choice.
Merlin star Colin Morgan talks about the important events from episode 511 'The Drawing of the Dark.'