Gwen is mistaken for Morgana and kidnapped by the savage outlaw Hengist. Uther refuses to pay her ransom, so Arthur defies his father and heads out into dangerous enemy territory to fight for Gwen's freedom. Merlin suspects Arthur's devotion to Gwen is more than that of a prince to one of his subjects. How will Arthur react when he discovers Gwen is not alone in Hengist's castle? She and Lancelot have found each other again, and powerful feelings rekindle.

For the first time in over 300 years the fires of Idirsholas burn and Gaius is worried that a sorcerer has revived the deadly Knights of Medhir. Morgause returns and is determined to end Uther's reign at Camelot.

The Great Dragon is finally free. Full of rage, he attacks Camelot with pitiless intensity. The castle is crumbling and Arthur's men cannot hold out much longer but only a Dragonlord can kill a dragon and Uther wiped them all out years ago. Or did he? Gaius admits one such man could still be alive and in hiding.

The last Dragonlord is the key to Merlin's own past as well as the future of Camelot, but will Arthur and Merlin find Balinor in time to save the kingdom?

Evil sorceress Morgana summons mighty gatekeeper the Cailleach, who opens a door to another world from which hellish creatures pour forth. As Arthur and his loyal knights take up arms, Merlin discovers the only thing that will stop them is an unimaginable sacrifice.

The kingdom is on the brink of collapse and Morgana poised to strike, in the final part of this opening episode of the fantasy drama. As Lancelot races back to Camelot with the dying Merlin, Arthur must continue on his mission to vanquish the Dorocha without them. Though the Knights know their journey to the Isle of the Blessed is fraught with danger, none could anticipate the sacrifice Arthur intends to make there.

Friendship and loyalty are tested to the limit, but in the end, it's the power of love that changes all their lives for ever.

Morgana joins forces with enigmatic wizard Alator to uncover a secret that could change the course of destiny, as the magical drama continues. With allies on both sides of the castle walls, can anyone stop her before Merlin's greatest secret is revealed?

A mysterious illness draws Merlin to a distant village. But it soon becomes clear that there is more at stake than just his patients' well-being as something sinister turns the air sour. Far from home and with no-one to trust, Merlin becomes embroiled in a deadly game of cat and mouse. No longer sure who is the hunter and who is the hunted, can the young warlock survive long enough to uncover the truth?

With Princess Mithian as the perfect bait, Morgana conjures a deception so powerful that the whole of Camelot is taken in - even Merlin himself. But as the storm clouds gather, will the young warlock see through the lies? Or will Morgana at long last fulfil her dreams of revenge?

When Gwen is snatched from Camelot without warning, Merlin knows there can be only one person responsible: Morgana. Arthur is determined to rescue his Queen – but it's not going to be easy, for she is locked in the Dark Tower, a place that haunts the dreams of men.

Arthur and his Knights must embark on a quest like no other, battling through a landscape riddled with hidden dangers, perilous obstacles and magical beings. As they near their goal, Merlin's sense of dread reaches breaking point. What twisted game is Morgana playing? And more importantly, just what is the final test that awaits them in the tower?