This episode is Dark Hook’s origin story. He rises the same way Emma did encased in black goo. He has also re-lived all of his worst memories to prepare for his new role. Just like Emma, Hook sees Rumple, but Hook is less excited to see his enemy. But Rumple makes him an offer: He can get him the revenge he has always wanted, which includes killing Rumple for good.
Hook wipes Emma’s memories with her dreamcatcher right before the group arrives at her house. After finding her pretty much incapacitated (Zelena put her magic-removing cuff on her before she left), they find out what happened to Hook. Regina is not happy Emma made him a Dark One, but Emma says she thought she was doing everyone a favor by isolating herself and not getting everyone involved. Snow asks her to give them back their memories because if they know what happened they can defeat Hook, but David appears and tells them all the dreamcatchers are gone.
Hook has made his way to Rumple and Belle. He wants to get his revenge that he was promised. He tells Rumple they are fighting on his ship; him with Excalibur (which can kill him) and Rumple with a regular sword. Rumple goes to the group and brings up Merlin’s message about Nimue, which Emma recognizes. She wants them to take off the cuff, but no one trusts her. Even Henry refuses to help.
Rumple goes to Belle and says he isn’t going to run because that’s all he has ever done. Belle says he has nothing to prove anymore, but he disagrees. He wants to do better by her. He asks her to meet her at the well after the battle.
Emma comes to Rumple to ask for his help to give everyone their memories back. She wants him to occupy Hook in the battle long enough for her to steal the dreamcatchers. Rumple isn’t interested in using magic to win the battle, but he is going to fight Hook. Emma finds Henry in the library and he offers to make her a locator spell to find the Dreamcatchers. Emma has convinced him so he removes the cuff.
Zelena goes to visit her baby only to see Regina has already removed her. She brings Zelena to where Robin is taking care of the child hoping the child will change Zelena. Robin permits Zelena to visit the child as long as he and Regina are there.
Rumple meets Hook on a ship. Hook wounds him, but Rumple gets the upper hand and instead shows him mercy rather than killing him. Rumple wants Hook to live knowing he was bested by Rumple. Rumple goes to the well where Belle meets him. She loves him, but he has hurt her too many times to continue the relationship.
Merlin and the others are trying to find out where Emma and Hook went. Snow suggests going to the Lady of the Lake for help and then defends Emma’s decision to save Hook. Emma finds Hook and tries to talk some sense into him like how he did when she first became the Dark One. She is able to lure him away from Rumple with love. She is still determined to get the darkness out of both of them.
Emma and Hook are sharing a kiss. Hook gets distracted by Rumple who tells him that Emma is lying about not knowing where Excalibur is. She has it because he can hear the dagger. When Emma returns he calls her out for lying and she admits she kept the sword because she knew he was afraid of his powers. Hook yells at her for turning him into the Dark One when he asked her not to. Hook used love and trust to try to save her, but she went straight to dark magic and never believed in him.
When Emma summons him with the dagger, she argues that the reason she saved Hook is because she couldn’t bear to lose him. She gives him the sword to show she does trust him. Before they kiss, Emma promises to destroy the darkness together.
Emma returns to her family, claiming he can be trusted. Hook enters Granny’s where Merlin is recording his message about Nimue. In order to get his revenge on Rumple, Hook needs to get back to Storybrooke, but to get that spell he has to crush the spell of the thing they love most. Hook takes Merlin’s heart and then Nimue appears. If Hook crushes Merlin’s heart, it will be just like his lover did it. Emma comes in, upset Hook played her, but Hook still crushes Merlin’s heart. He uses Merlin’s heart to create a relocation spell, but Emma knocks him out and steals his memories in order to make him the man he was before the darkness took over. Rumple appears and reminds her she will need to erase the memories of everyone who knew about Hook being the Dark One.
Everyone is at Regina’s as Emma prepares to give them back their memories and her own. Once she does, she remembers exactly what Hook is going to do. We see Hook and Rumple at the lake, which holds the portal to the Underworld. He uses a drop of Rumple’s blood from the duel to open it. The portal opens and a boat rows over. Nimue reveals herself and the rest of the Dark One Army. They are going to do what Dark Ones do best which is snuff out the light.