A pair of quests led to the thrilling finale of the episode. It was nicely tied together to introduce the big pay-off.
In Camelot, Emma and Merlin went in search of the jewel that would join the dagger with Excalibur. On their journey, Merlin tells Emma the original Dark One killed the woman he loved.
Merlin told of meeting the woman he loved, Nimue, and eventually wanting to marry her but told her he couldn’t because he was immortal. He told her he found the Holy Grail and drank from it, giving him immortality and magic. They came up with a way to be with each other – take the Holy Grail and turn it to something else.
As Merlin and Nimue convert the Holy Grail, the masked man that had been secretly stalking them reveals himself to them. Merlin tells him the Holy Grail is gone and Nimue goes after him and he stabs and kills her. Merlin is devastated until he discovers Nimue didn’t die and she pulls out the masked man’s heart – he was the one who killed her family.
Merlin warns Nimue that if she destroys the man’s heart, she will embrace the darkness of magic. She doesn’t heed his warning and crushes the man’s heart. Her skin slowly turns sparkly green as the darkness overtakes her. She tries to break the sword that was created from the Holy Grail but the tip breaks off, which Merlin turns into the dagger that can control the one wielding the darkness.
As Emma and Merlin reach the spot of the eternal flame, the evil Nimue appears and it is then Emma realizes the first Dark One was Merlin’s love. Nimue tries to turn Emma, who fights her off and grabs the jewel – the dagger and Excalibur can be combined.
It is up to the others to try and find a way to get Excalibur from Arthur. They enlist the help from Zelena who says she knows a secret way in. Mary Margaret is charged with staying with Zelena, but Mary Margaret is doped by Zelena and she ties her up.
When they make their way to Arthur, he is first surprised to see David, Regina, Hook and Robin Hood. Arthur has a surprise of his own, as it is revealed Zelena is working with him as she comes in with a tied up Mary Margaret. Zelena uses a binding spell to put Merlin’s name on Excalibur so Arthur can control him. He calls Merlin and has him send the group opposing him away.
Back in Storybrooke, Dark Swan Emma uses the jewel to combine the dagger and Excalibur. All the former Dark Ones urge her to grasp the sword. For a moment, she remembers Merlin’s warning to her as a young child to not touch the sword. She doesn’t listen in the end and takes the sword.