<Li> Gordon Munro as Alrick </Li> <Li> John Shrapnel as King Sarrum </Li> <Table> <Tr> <Th> No . overall </Th> <Th> No. in series </Th> <Th> Title </Th> <Th> Directed by </Th> <Th> Written by </Th> <Th> Original air date </Th> <Th> UK viewers (millions) </Th> </Tr> <Tr> <Th> 53 </Th> <Td> </Td> <Td> "Arthur's Bane - Part 1" </Td> <Td> Justin Molotnikov </Td> <Td> Julian Jones </Td> <Td> 6 October 2012 (2012 - 10 - 06) </Td> <Td> 7.12 </Td> </Tr> <Tr> <Td_colspan="7"> Camelot is three years into her Golden Age, but already the seeds of her destruction are being sown . After news that Sir Gwaine and a battalion of Camelot's finest were lost in a patrol in the northern lands of Ismere, Camelot's round table comes to the conclusion that Morgana is behind this . Arthur sets off on a perilous journey with Merlin and a handful of knights to rescue the men . On the way, Merlin is shown a frightening vision of Arthur's death . Meanwhile, behind the walls of Camelot, Queen Guinevere must seek out a traitor who has put everyone's lives at stake . </Td> </Tr> <Tr> <Th> 54 </Th> <Td> </Td> <Td> "Arthur's Bane - Part 2" </Td> <Td> Justin Molotnikov </Td> <Td> Julian Jones </Td> <Td> 13 October 2012 (2012 - 10 - 13) </Td> <Td> 6.99 </Td> </Tr> <Tr> <Td_colspan="7"> Merlin is troubled by Mordred's reappearance, despite the kindness the latter shows to both Merlin and Arthur . After escaping from the Saxons, Merlin and Arthur continue their journey to Morgana's tower in Ismere, while Mordred travels with the Saxons on the same path . In the tower, Arthur and Merlin disguise themselves as Saxons, but Arthur is intercepted by Morgana . Merlin attempts to save him but is incapacitated . Mordred ultimately saves Arthur in an unexpected turn of events . He is then knighted in Camelot, but Merlin is still wary of him . </Td> </Tr> <Tr> <Th> 55 </Th> <Td> </Td> <Td> "The Death Song of Uther Pendragon" </Td> <Td> Justin Molotnikov </Td> <Td> Howard Overman </Td> <Td> 20 October 2012 (2012 - 10 - 20) </Td> <Td> 6.86 </Td> </Tr> <Tr> <Td_colspan="7"> When given the chance to see his father one last time, Arthur takes it . Little does he know, however, that Uther is one step ahead of him, and his actions have devastating consequences . With Uther's spirit on the rampage in Camelot, Merlin knows that they must work fast to eradicate the ghost of the old king . Thus, Arthur must hunt down his father and prove to him, once and for all, that he is now truly King . </Td> </Tr> <Tr> <Th> 56 </Th> <Td> </Td> <Td> "Another's Sorrow" </Td> <Td> Ashley Way </Td> <Td> Jake Michie </Td> <Td> 27 October 2012 (2012 - 10 - 27) </Td> <Td> 6.86 </Td> </Tr> <Tr> <Td_colspan="7"> When Princess Mithian of Nemeth, a long - standing ally of Camelot, comes to Arthur seeking aid as her father has been captured by the long - time enemy of Camelot, Odin, he is quick to grant it . But Merlin fears there is something sinister at play, particularly due to the odd behavior of Mithian's nurse, Hilda . Unable to persuade the king of his suspicions, Merlin joins Arthur, Gaius, Mithian, Hilda, and a handful of knights on a journey to rescue Mithian's father, Rodor . </Td> </Tr> <Tr> <Th> 57 </Th> <Td> </Td> <Td> "The Disir" </Td> <Td> Ashley Way </Td> <Td> Richard McBrien </Td> <Td> 3 November 2012 (2012 - 11 - 03) </Td> <Td> 6.88 </Td> </Tr> <Tr> <Td_colspan="7"> The Disir summon King Arthur to receive the judgement of the Triple Goddess and Arthur decides to respond . All does not go as planned, and the King and his knights' recklessness leave Mordred gravely wounded . Desperate, Arthur decides to petition the Disir for help, and he and Merlin seek them out again . The Disir give Arthur an ultimatum: embrace magic, or the Triple Goddess will seal his fate against him . Merlin seizes what he sees as the opportunity to kill Mordred and reminds Arthur that there is no place for magic in Camelot . The Disir seal Arthur's fate and when he returns, Mordred is well again . Merlin realises only then what happened; in not embracing magic, Arthur sealed his fate; Mordred lives . </Td> </Tr> <Tr> <Th> 58 </Th> <Td> 6 </Td> <Td> "The Dark Tower" </Td> <Td> Ashley Way </Td> <Td> Julian Jones </Td> <Td> 10 November 2012 (2012 - 11 - 10) </Td> <Td> 6.85 </Td> </Tr> <Tr> <Td_colspan="7"> Gwen and Elyan are on a pilgrimage to their father's grave . However, on the journey back, Gwen is captured by Morgana . At the news, Arthur and his knights ride out on a rescue mission . Morgana begins a slow process of torturing Gwen using mandrake root . Arthur and the others arrive at the Dark Tower, where Gwen is kept, and Elyan surges ahead, finding his sister trapped by a magically protective sword . He fights with the sword until he dies in Gwen's arms . Arthur brings Gwen back to Camelot where Elyan's funeral is held . However, at night, Gwen sneaks to a meeting with Morgana as they begin their conspiracy against Camelot . </Td> </Tr> <Tr> <Th> 59 </Th> <Td> 7 </Td> <Td> "A Lesson in Vengeance" </Td> <Td> Alice Troughton </Td> <Td> Jake Michie </Td> <Td> 17 November 2012 (2012 - 11 - 17) </Td> <Td> 6.86 </Td> </Tr> <Tr> <Td_colspan="7"> Strange events are occurring in Camelot, and all of them seem to bring harm to the King . Tyr, a stable - hand, gets caught in the cross-fire and Morgana fears that he will reveal the secret of Guinevere being a traitor . Merlin becomes suspicious of Gwen, quickly realising that Morgana must have done something to her . Tyr is found dead before he can report any news, and the attempts to kill Arthur continue . Finally, Gwen manages to poison Arthur, forcing Merlin to use his magic to save the King . </Td> </Tr> <Tr> <Th> 60 </Th> <Td> 8 </Td> <Td> "The Hollow Queen" </Td> <Td> Alice Troughton </Td> <Td> Julian Jones </Td> <Td> 24 November 2012 (2012 - 11 - 24) </Td> <Td> 6.86 </Td> </Tr> <Tr> <Td_colspan="7"> When Daegal, a Druid boy, asks for Merlin's aid in helping his sick sister, Merlin agrees and begins the journey to the Valley of the Fallen Kings . This turns out to be a trap for Merlin set by Morgana . Daegal reconsiders, and saves Merlin . In the meantime, Arthur is entertaining the fearsome Lord Sarrum with peace treaties . Guinevere plots Arthur's assassination with the visiting warlord . Morgana and Gwen plan to double cross Sarrum, but Sarrum plans to do the same . On the day of the treaty signing, Sarrum positions an assassin to kill Arthur . Merlin and Daegal arrive just in time to save Arthur and kill Sarrum, but Daegal dies in the process . Merlin and Gaius bury Daegal, and Merlin knows that something must be done about Gwen . </Td> </Tr> <Tr> <Th> 61 </Th> <Td> 9 </Td> <Td> "With All My Heart" </Td> <Td> Alice Troughton </Td> <Td> Richard McBrien </Td> <Td> 1 December 2012 (2012 - 12 - 01) </Td> <Td> 6.76 </Td> </Tr> <Tr> <Td_colspan="7"> Merlin reveals Guinevere's betrayal to Arthur . Merlin resolves to bring the old Gwen back and Gaius suggests that he travel to the Dochraid . Under threat, the Dochraid explains that Gwen must enter a magic lake willingly to be cleansed by the White Goddess . Arthur, Merlin and Mordred take the unconscious Gwen to the lake where Merlin takes on the guise of Dolma, a female sorceress, to perform the ceremony . Arthur must use Gwen's love for him to convince her to enter the lake . Merlin, still in disguise, asks Arthur not to forget that magic saved his Queen . Mordred confronts Merlin on the way back knowing that the magic that saved Gwen was his . </Td> </Tr> <Tr> <Th> 62 </Th> <Td> 10 </Td> <Td> "The Kindness of Strangers" </Td> <Td> Declan O'Dwyer </Td> <Td> Richard McBrien </Td> <Td> 8 December 2012 (2012 - 12 - 08) </Td> <Td> 7.00 </Td> </Tr> <Tr> <Td_colspan="7"> Morgana is determined to discover Emrys' identity . She captures Alator, who possesses this knowledge, but he refuses to reveal it . Meanwhile, a mysterious woman tells Merlin to meet her in the woods . Merlin goes, and finds she is a follower of Alator, named Finna . They are attacked by knights from Camelot, and Finna flees . Morgana finds a note sent from Finna to Alator and begins searching for her . Merlin reaches her first and they talk, before being attacked by Morgana's men . Merlin is wounded, but they manage to escape and Finna delivers Arthur's destiny to Merlin . She takes Merlin's sword and tells him to flee . Morgana arrives and confronts Finna, asking for Emrys' identity, but Finna commits suicide with Merlin's sword . </Td> </Tr> <Tr> <Th> 63 </Th> <Td> 11 </Td> <Td> "The Drawing of the Dark" </Td> <Td> Declan O'Dwyer </Td> <Td> Julian Jones </Td> <Td> 15 December 2012 (2012 - 12 - 15) </Td> <Td> 7.34 </Td> </Tr> <Tr> <Td_colspan="7"> Kara, a Druid girl and Mordred's love, is involved in a Saxon attack on a Camelot supply wagon . Mordred lets her escape and treats her injuries . Kara is discovered by Arthur and arrested after attempting to kill him . She is sentenced to hang . Mordred makes an unsuccessful attempt to flee with Kara, and they are both jailed . Arthur gives Kara the chance to repent . She refuses, and her sentence is carried out . Mordred breaks his cell open in a magical rage as Kara is hanged . He seeks Morgana, joins her forces and reveals Emrys' identity . </Td> </Tr> <Tr> <Th> 64 </Th> <Td> 12 </Td> <Td> "The Diamond of the Day - Part 1" </Td> <Td> Justin Molotnikov </Td> <Td> Jake Michie </Td> <Td> 22 December 2012 (2012 - 12 - 22) </Td> <Td> 8.45 </Td> </Tr> <Tr> <Td_colspan="7"> Morgana succeeds in stripping Merlin of his magic and he is helpless to aid Arthur who has decided to meet Morgana's forces at Camlann . To regain his magic Merlin travels to the Crystal Cave in the Valley of the Fallen Kings . Using a spy, Morgana tracks and entombs Merlin in the Cave . Awakened by a vision of his father, Merlin's magic is restored and he warns Arthur of Morgana's battle plans while the King sleeps . The battle commences and Merlin emerges from the Cave as Emrys . </Td> </Tr> <Tr> <Th> 65 </Th> <Td> 13 </Td> <Td> "The Diamond of the Day - Part 2" </Td> <Td> Justin Molotnikov </Td> <Td> Julian Jones </Td> <Td> 24 December 2012 (2012 - 12 - 24) </Td> <Td> 7.80 </Td> </Tr> <Tr> <Td_colspan="7"> Emrys arrives at Camlann, and uses his magic to knock Morgana unconscious, order Aithusa to leave, and strike down many of Morgana's men . The battle culminates in Mordred dealing Arthur a fatal wound, only to receive one in return . While tending to Arthur, Merlin confesses that he is a sorcerer . Arthur's only chance of survival is the powers of the Sidhe of Avalon, so Merlin sets out to reach the lake . In Camelot, Morgana's spy is discovered and hanged, leading Gwaine, along with Percival, to hunt down Morgana . However, she overpowers them and magically tortures Gwaine into confessing Arthur's whereabouts; Gwaine passes out shortly afterwards in Percival's arms . Morgana catches up with Merlin and Arthur and drives their horses away, but she is killed by Merlin wielding Excalibur . Without horses, Merlin cannot get Arthur to the Isle in time, and the King of Camelot dies in Merlin's arms, after thanking his friend for everything he has done . Merlin beseeches the Great Dragon to carry Arthur's body to the Isle, and the Dragon does so . As Merlin desperately tries to drag Arthur's body to the lake, the Great Dragon tells Merlin he has succeeded, and that as the Once and Future King, Arthur will rise again in Albion's greatest hour of need . As the Dragon departs, Merlin flings Excalibur into the waters of Avalon and sends Arthur's body after it . Guinevere ascends the throne of Camelot . In the present day, it seems an immortal Merlin still waits for the Once and Future King to rise again . </Td> </Tr> </Table> <Tr> <Th> No . overall </Th> <Th> No. in series </Th> <Th> Title </Th> <Th> Directed by </Th> <Th> Written by </Th> <Th> Original air date </Th> <Th> UK viewers (millions) </Th> </Tr>

When does king arthur find out about merlin