The Diamond of the Day Part II
And after that cliffhanger from last time, the episode opens exactly where we left off: in the middle of a huge battle, with Merlin riding to the rescue. The Knights and Saxons fight, with Arthur and Mordred putting their dragon-forged swords to good use. Gwen and Gaius are back in the tents, treating knights when one stumbles in, followed by a Saxon. Gwen kills him, but it's clear they're being pushed back. Soon enough, reinforcements arrive on both sides: the rest of the Saxon army, Aithusa and Merlin.
Merlin starts using lightning against the troops, causing a full retreat. He blasts Morgana too and banishes Aithusa. Gwen notices the man on the cliff, and Gaius tells her he's someone truly remarkable and that he deserves their gratitude. Gwen looks thoughtful.
Meanwhile, Arthur is wandering through what's left of Saxons and comes across Mordred, who wastes no time in fulfilling the prophecy: he stabs Arthur, and Arthur falls. Mordred takes a moment to check, and Arthur leaps up and stabs him. Mordred collapses, a creepy smile on his dying face. Merlin comes down to look for Arthur, and picks him up and carries him away.
Arthur wakes up at a camp Merlin set up, and even if he tries to laugh the pain off, it's plain that he's going to die. Merlin, sobbing hard, apologizes for failing to avert the prophecy. Arthur asks him what he's talking about. Merlin continues talking, saying that he drove off the army. Arthur tells him that that wasn't him, it was the sorcerer. Merlin tells him the truthnote
, and Arthur refuses to believe him. Merlin turns to the fire, muttering a spell and causing a dragon to appear in the sparks. Arthur tells Merlin to leave him alone to think for a moment.
Back at the castle, Gwen is searching for Arthur. Leon tells her that three patrols have not found him, and then reveals that Gaius is missing too. Gwen puts two and two together and assumes Gaius is tending to Arthur.
An assumption that turns out to be correct when we cut to Gaius tending Arthur. Merlin goes off to find some supplies and Arthur tells Gaius about Merlin's magic, only to realize that it's no surprise to Gaius. Gaius tells Arthur that Merlin is not just a sorcerer, but the greatest one who ever lived, and he's the only chance he's got. Later, he talks to Merlin, telling him there's still a shard of the sword in his body, and in order for him to heal, he needs magic of equal age: that of the Sidhe. Merlin decides to take him to Avalon, and Arthur gives his seal to Gaius, telling him to give it to Gwen so that she can assume the throne.
Meanwhile, Morgana has buried Mordred, telling him she will get revenge for him. She force-chokes one of her soldiers to death for bringing her the bad news, and sets her final plan in motion, waiting for information from her mole on Arthur's location.
Back at the castle, Gaius passes the sad news on to Gwen, who is distressed but accepts that Avalon's the only way to save Arthur. Eira asks Gwaine where Arthur is, and he tells her. She's later caught by Gwen after sending the last bit of raven post this season, and Gwen reveals that she's sent Morgana the wrong location. Eira pleads for Gwaine to help her, but to no avail.
Arthur and Merlin are traveling to Avalon when two Saxon soldiers catch up to them. Merlin puts on a ruse of being attacked by Camelot knights and asks for their help, but they figure out the truth. Merlin kills them, causing Arthur to note that he's lied to him this whole time. Merlin doesn't respond.
Later that night, Merlin is lighting the fire. Arthur asks him why he doesn't use magic, and Merlin says it's just habit. Arthur gives him the go-ahead, and he lights it and takes off Arthur's boots, saying they need drying. The next morning, Merlin's prepared breakfast and starts feeding it to Arthur. Arthur asks him why he's still behaving like a servant, and Merlin says it's his destiny to serve Arthur. Both remember their first fight, and Arthur accuses him of cheating when he reveals that he used magic in the fight. Merlin then tells him the other reason: that Arthur's his friend and he doesn't want to lose him. Arthur's quiet.
Back at Camelot, Gwen calls Gaius to the Round Table. She then asks him if he knew who the sorcerer in the battle was. Gaius tells her yes, and Gwen asks if it's someone she knows with a smile on her face. Gaius confirms her suspicions in the same vague way, and she notes that Arthur's in the best care he could be. That's right, after five seasons, Gwen has finally guessed the truth.
Gwen executes Eira for her treason, and Gwaine swears revenge on Morgana. Percival accompanies him, riding to where they sent Morgana.
Merlin and Arthur talk, with Arthur asking him why he didn't tell him. Merlin answers with the obvious: Arthur would have killed him. Arthur isn't sure that he would have done so, and Merlin tells him he wanted to spare him the choice. Arthur is surprised with this decree of loyalty, and Merlin tells him that he's happy with his destiny to serve Arthur, and he wouldn't change a thing.
Meanwhile, Gwaine and Percival attack Morgana's entourage, killing all the Saxons. Gwaine goes behind her, causing her to turn around...and letting Percival get a blade to her back. She cries out in pain... and then recovers, knocking out both of them. She's a High Priestess after all, and no mortal blade can kill her. She ties up Percival and brings out her Nathair to torture Gwaine. Percival hears Gwaine screaming, and rips his way out of his restraints, running to Gwaine's side. Gwaine tells him that Morgana's heading toward Avalon, and dies in Percival's arms, Percival quietly mourning him.
Merlin is riding with Arthur, and uses his mind's eye to see the path ahead, manuevering them out of the Saxon's way. He then covers their tracks and distracts the soldiers, causing Arthur to note that he's not an idiot, and ask why he never attempted to take credit. Merlin tells him that's not why he does it, and goes on his way. Later that night, Arthur apologizes for how he treated Merlin in the past, and makes no secret of the fact that he thinks he won't survive to Albion. He tries to allay the tension by joking he'll give Merlin two days off. Merlin laughs, but knows him too well to buy it.
Morgana heads out on their trail, and finds Merlin, knocking him out and gloating to Arthur about how he's won the battle but lost the war. Merlin grabs Excalibur, and she tells him that no weapon forged by man can kill her. Unfortunately for her, Excalibur was forged in a dragon's breath, and Merlin kills her with it. Arthur notes she's finally peaceful with regret in his voice.
They keep going, until they reach a field and Arthur finally collapses. Arthur's dying, even if Merlin refuses to accept it. He uses his last words to thank Merlin for all he's done, and finally dies. Merlin, desperate, calls the dragon, and Kilgharrah arrives to take them both to Avalon. Merlin mourns both his friend and his failure, and Kilgharrah told him that he hasn't failed: Arthur will return when he is needed once more. Merlin throws Excalibur into the lake, and a hand reaches up and grabs it. He puts Arthur on a boat, and sends it towards the isle of Avalon, saying his final goodbye.
Back at Camelot, it appears that they've accepted the truth. Leon announces Arthur's death, and everyone, including a still mourning Percival, chants their praise to their new queen regnant as Merlin's theme plays with vocals, strings, and all. Guinevere holds Arthur's seal in her hands, looking devastated - but also resolute as "long live the Queen!" echoes around the hall.
We cut back to the isle of Avalon, and a lorry flies past down a modern road. Merlin, aged either naturally or by magic, is walking down the road as he did in the beginning of the series. He looks out hopefully towards the isle, and then keeps walking, still waiting for Arthur's return.