The Storybrooke Town Hall appears in the forest.
In the hours after Hades and Zelena return to Storybrooke, Zelena goes off to find the others and leaves the baby with Hades. While she is gone, King Arthur, who just escaped from the jail and is being tracked down by Snow White, Merida, and the dwarves, meets up with Hades, but he kills Arthur as he sees him as a threat. Zelena finds Regina and Robin Hood and tries to convince them that Hades has changed his ways. Emma, David, and Henry are reunited with Snow and Merida and explain the details of Hades' deception but Emma's vengeance against Hades is making her too emotional. Zelena and Hades are talking about the others not believing that he changed. Hades gets a weapon, known as the Olympian Crystal, which can kill anybody, even a god. He also suggests that they leave Storybrooke but Zelena is not so sure if she wants to. As Emma, Merida, and David find Arthur's body at the Storybrooke Bridge, David tries to calm down a furious Emma, who's trying to protect Storybrooke from Hades' wrath.
Meanwhile, Gold goes to Belle's father Moe to see if he can give Belle true love's kiss to wake up Belle from the sleeping curse she put herself under, but Moe refuses. Emma then shows up asking Gold for help defeating Hades, but Gold declines to help. Gold later calls Hades to offer him a deal by protecting him in exchange for the Crystal, only to have Hades turn down the offer.
Back at Regina's office, Hades is able to put back together the Olympian Crystal with Zelena's help. Zelena then sees Emma trying to break the protection spell that Zelena put on the town hall knowing that Emma want to kill Hades (after she saw the new pages appear in front of her), leading to a confrontation between the women. Back inside the town hall after they entered through a tunnel, Regina and Robin uses Zelena's distraction to take the baby, only to be caught by Hades, who then uses the crystal to kill Regina, but Robin sacrifices himself as he saves Regina from being killed by Hades, then Zelena comes in and realizes that Hades never changed and kills Hades instantly by stabbing the Olympian Crystal through his heart. Later, Emma, Henry, Mary Margaret, David, Regina, Zelena, and others attend Robin Hood's funeral. Emma decides to stay for a couple more minutes, and notices a resurrected Hook, who was brought back by Zeus as a reward for helping to defeat Hades, and the two are happily reunited. During this time, Mr. Gold comes inside Regina's office, and it is revealed that a piece of the Olympian Crystal is still around, which Mr. Gold collects for a new plan.
In the Underworld
King Arthur comes inside the Underbrooke diner, confused and not knowing that he is dead, until he is reunited with Hook, who asks for his help in stopping Hades. King Arthur agrees to help him. Later, Hook and King Arthur searched Hades' lair where they find Hades' story, when Arthur realizes that the only way that Hades keeps his secrets would be inside his throne just like Arthur would do. Shortly after that, Hook and King Arthur learn from Cruella that the "Once Upon a Time" book is near the Sea of Lost Souls, and when Hook and King Arthur find it there the lost Souls attempt to take it and Arthur but thanks to Hook he saves both Arthur and the book, where they discover the only was to destroy Hades is by using the Olympian Crystal, and Hook uses the book to magically reach the living successfully (after Emma sees it). Later, King Arthur decides to stay in the Underworld, and Hook steps into the light of Mount Olympus & he meets Zeus, who then shows Hook the way back to the land of the living. Hook tells a happy Emma that Zeus rewarded him with a second life.
- This is the last episode to feature the Underworld.
- This is the last episode to feature Hades.