Merlin is still too weak to walk back to Camelot but, with the young wizard on his back, the Great Dragon speeds through the moonlit clouds. On arrival, Merlin warns Gaius of Morgana and Morgause's alliance and the impending doom awaiting Camelot. They rush to Uther's chambers and are greeted by the king, gripped by insanity. Knowing the source of Uther's mental torture, Merlin throws the mandrake root into the fire and its magical screams fill his head.
Merlin wants to enlighten Uther on Morgana's twisted plot, but Gaius tells him that to make such an accusation against his beloved ward would be an act of treason. Morgana is gripped by panic when she sees Merlin is still alive. She hurries to Uther's chambers in search of the mandrake root. Gaius catches her and, feigning ignorance, explains Uther was being enchanted. Morgana hides her frustration well, until Gaius' back is turned.
A hastily convened council of war is in session, and Arthur hears of the threat from Cenred. Defiant, he will not bow down to the invaders. He finally takes his place in the King's seat and tells the council to prepare for a siege.
Morgana warns Morgause about Merlin and the destruction of the mandrake root. Cenred's army is still en route, so their plan has not yet failed. Morgause gives Morgana a sacred staff carved from the rowan tree that grows at the very heart of the Isle of the BlessedMorgana is worried about her magical abilities, but the staff contains its own power, and will aide Cenred's army.
The warning bell sounds, Cenred's army is at the gates of Camelot. Morgause and Cenred stand together staring up at the mighty citadel. A fireball arcs up into the night sky, exploding with terrifying force in the streets of the Lower Town. The siege has begun.
Uther wakes from the sounds of the battle around him. Though still weak, he drags himself up out of bed, emerges from the royal palace and takes in the devastation. Thanks to Merlin, he may not have lost his mind, but if Arthur fails he may still lose his kingdom.
Arthur orders his men to fall back as, to his surprise, Uther joins the fray. Arthur rushes to his father's aide, but Cenred's men are bearing down on them. Merlin, having just made it back, risks discovery and utters a spell, sending the men flying. Cenred and Morgause celebrate taking the Lower Town, but they know true history will be written once the citadel is theirs. First, Morgana must first fulfil her role.
Seeing that Gaius is distracted, Morgana retrieves the magical staff and heads to the vaults. She raises the powerful staff high above her head and plunges it down through the solid rock. The power of the staff erupts through Camelot, alerting Morgause to its presence. Morgause tells Cenred that the time is right; not even the great Knights of Camelot can fight a war on two fronts. Morgana watches, enthralled, as a skeletal hand emerges from the broken tombs.
Merlin and Arthur stare in horror as three skeletons march slowly toward them. Arthur launches himself into battle with one of them, and Merlin fights, too, but the fiendish creatures just keeps coming. Merlin knows Morgana is behind this dark twist of fate, and races to stop her.
Down in the vaults, a cold, menacing Morgana tells Merlin that, without magic, he will never understand. Merlin hesitates; Morgana's words have resonance with him, but it does not change the fact people are dying at her hand. As he tries to grab the staff, Morgana draws her sword. It's the last thing Merlin wants, but they fight.
It's clear Morgana is the better swordsman. She disarms him but, with her back to him, he seizes the opportunity and utters a spell. A section of masonry crumbles and falls from the ceiling, knocking her out. Merlin enchants a sword and swipes at the staff, severing it in two.
A desperate and bandaged Arthur continues the futile battle with the skeletons. The Knights of Camelot have all but given up hope when, to their astonishment, the skeletons crumble to bones. With renewed vigour, Sir Leon leads his knights onto the drawbridge, forcing Cenred's men back. Victory belongs to Camelot.
A fully healed Uther addresses the court, thanking everyone for the victory and for defeating the traitor within Camelot. He wants to give a special thanks to the person who thwarted their plan and almost singlehandedly won the war. All eyes look around. Secretly, Merlin knows that it's him, but accepts he can never take the credit. He expects another knight to take the honour and glory, but is completely shocked when the King thanks...the Lady Morgana.
Morgana meets with Morgause. Morgause tells her sister she must return to Camelot and continue to play the role of the dutiful ward. As if hearing their conversation, Merlin confides in Gaius, the next time they try anything, he will be ready. Gaius warns him to be careful, but Merlin is not afraid of the evil sisters. Gaius, ever cautious, thinks he should be.
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.