The Darkest Hour is a two-part story consisting of the first and second episodes of the fourth series of Merlin. It is set a year after the occurrences in The Coming of Arthur.


Part One

Merlin faces his toughest challenge yet when Morgana's blinkered determination threatens not only Arthur's future, but also the very balance of the world. With her magic stronger than ever,

the sorceress summons the mighty Callieach to tear open the veil between the worlds.

Hellish creatures pour forth, killing all who succumb to their touch. With Uther a shadow of his former self, it falls to Arthur and his loyal knights, including Lancelot, to protect the kingdom, but it will take more than just swords to vanquish their enemy and Merlin is shocked to the core when he discovers the only way to restore the equilibrium requires a sacrifice of unimaginable proportions.

Part Two

The kingdom is on the brink of collapse and Morgana poised to strike. 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.


Part One

Sir Leon, Sir Elyan and two other knights of Camelot cross paths with Morgana in the middle of a wasteland, and are subsequently knocked unconscious by her magic. Morgana unwraps the cargo on her cart to reveal a disfigured and weak Morgause. Back in Camelot, life has just about returned back to normal, with the exception of Uther, who is still stricken and ill a year after Morgana's betrayal. Arthur's maternal uncle, Sir Agravaine, now acts as mentor and council to the prince.

Leon and Elyan return to court (the other two knights did not survive) to warn Arthur of Morgana. That night, as Camelot feasts, Morgana and Morgause arrive on the Isle of the Blessed, where the dying Morgause convinces Morgana to sacrifice her in order to tear open the veil to the other world and unleash otherworldly horror upon their enemies. Morgana hesitates, but upon Morgause's insistence, she complies. When the sacrifice is made, Morgana becomes unconscious and, miles away, so does Merlin. Both witness the arrival of The Cailleach, the gatekeeper of the "veil between our world and the next," who calls Merlin Emr

ys and tells Morgana that, though her enemies will suffer like never before, she also needs to be aware of Emrys, who is both her "destiny" and her "doom."

In Camelot, Gaius suspects that the veil to the underworld has been torn, most definitely by Morgana. A girl from a town in the outskirts arrives, telling Arthur and the knights about the death of her village at the hands of beings that had no faces but could be heard by their screams. Gaius identifies these creatures as the Dorocha, the spirits of the dead. When Arthur, the knights and Merlin visit the village, Merlin and Lance discover that Merlin's magic does not work in the presence of the Dorocha.

The Dorocha attack Camelot, and the only way to repel them is with fire and light. The castle dungeons are soon filled with corpses of victims who have been frozen to death at the touch of the Dorocha. People from all over the lower towns gather in Camelot for protection, and Percival and Elyan nearly lose their lives while saving three children from the Dorocha in town. Merlin grows terrified of the Dorocha because his magic is useless against them, telling Gaius that he has never felt so weak. When he asks the seemingly at ease Arthur whether the prince is afraid, the latter confesses that he is probably more afraid than Merlin.

Arthur, Agravaine and Merlin learn from Gaius that the only way to close the veil may be to travel to the Isle of the Blessed and make another sacrifice. Arthur volunteers himself and goes to tell the inert Uther about his decision. As he is about to leave, Uther suddenly takes his hand and asks him not to leave, to which Arthur replies through tears that he must. Gwen, who is taking care of Uther, also asks Arthur not to go, but he makes her smile by asking her if she remembers the time he first kissed her. Merlin also prepares to depart; when Gaius asks him not to seeing as his powers don't work against the Dorocha, Merlin reveals his plan to sacrifice himself in place of Arthur. Meanwhile, Agravaine visits Morgana in her hiding place to inform her of Arthur's plan.

Arthur, the Knights of the Round Table and Merlin leave for the Isle of the Blessed. Lance continually encourages Merlin to leave and protect himself, but Merlin refuses. The group gets a fire going and Arthur and Merlin go collect more firewood, but one of the Dorocha attacks them and they lose their torch. The remaining knights, with only one torch left between them, decide to search for Arthur and Merlin. Hiding in an abandoned room, Arthur and Merlin attempt to reassure each other and Arthur tells Merlin that he is "a brave man," then joking adds "between battles." Merlin replies, "You have no idea how many times I've saved your life," to which Arthur says if he ever becomes king, he will make Merlin the court jester.

One of the Dorocha finds Merlin and Arthur's hideout as Lance and the others battle their way through the disheveled castle with only one torch. As Arthur is about to rise, Merlin shoves him down and jumps to face the Dorocha himself, jumping straight though it and being flung across the room and hitting the wall.

Lance and the other knights barge into the room and vanquish the Dorocha. The knights rush to Merlin's still form slumped by the wall. Part I ends with Arthur turning over Merlin's limp body and seeing that his face is frozen and apparently dead.



Part One October 1 2011 - 7.50pm BBC One and BBC One HD

Part Two October 8 2011 - 8.05pm BBC One and BBC One HD


First preview clip

More preview clips


  • The Darkest Hour (Part One) is the first episode of Merlin to air on the same night as an episode of fellow BBC Saturday night drama, Doctor Who. As the finale of Doctor Who Series 6, The Wedding of River Song, is to be broadcast right before the first episode of Series 4.
  • A new opening sequence is introduced for Series 4, the one used for the first three series only used clips from Series 1, while this one uses clips from all four series. Kilgharrah's opening narration also changes slightly, he now describes Merlin as "a young man" rather than "a young boy".
  • As episodes of Merlin are repeated on the CBBC Channel on weekends, reruns of To Kill the King and Le Morte d'Arthur aired on the same day as Parts One and Two respectively.
  • This is the first time Kilgharrah speaks to someone apart from Merlin (and Gaius), as Lancelot meets him in Part Two.
  • Both the Wilddeoren (Lancelot and Guinevere) and the Wyvern (The Eye of the Phoenix) return in Part Two.
Series 4
The Darkest HourThe Wicked DayAithusaHis Father's SonA Servant of Two MastersThe Secret SharerLamiaLancelot du LacA Herald of the New AgeThe Hunter's HeartThe Sword in the Stone
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