Original Release: September 27, 2015 (US)
Running Time: 44 minutes
The fifth season premiered on September 27, 2015 and the last episode of the season aired on May 15, 2016.
The characters embark on a quest to Camelot to find the Sorcerer Merlin (Elliot Knight) in order to free Emma from the powers of an ancient darkness that threatens to destroy everything. To complicate matters, King Arthur (Liam Garrigan) is determined to forever alter the balance between light and darkness using the legendary Excalibur. As history and destiny collide, unsuspected consequences lead the characters to the Underworld where they encounter souls of those with unfinished business and must face Hades (Greg Germann).
In an attempt to restore order to the chaos that has culminated, the characters' dangerous manipulations of magic lead to an exacerbation of the war between light and darkness, with the separation of Regina and her Evil Queen persona, as well as the arrival of Dr. Jekyll (Hank Harris) and Mr. Hyde (Sam Witwer).
They find a bewildered Emma, who is trying to track down Merlin, and along the way befriends Merida, while being guided by a dark apparition of Rumplestiltskin, who wants Emma to embrace the Darkness. After they meet up with King Arthur in their quest in Camelot, the residents return to Storybrooke six weeks later, with no memories of what happened in Camelot, while wearing completely different attires. And Emma is now a fully-fledged Dark One, who vows vengeance on her loved ones.
Regina begs Emma to save Robin, but despite Hook's plea not to, Emma does so, and results in Regina eventually paying the price. In Storybrooke, the residents, and the now-transplanted Arthurians, are becoming fearful of Emma as the Dark One, and Regina must step up when a demon called the Fury attempts to take Robin's soul as payment, due to Emma having saved him on Regina's behalf. Meanwhile, Hook is feeling that Emma's good side is no longer there, while Henry meets a girl named Violet. It is revealed that Emma brought the Excalibur sword with the stone to Storybrooke, but she can't pull out Excalibur to make it whole unless she pays the price.
She informs the newly awakened Gold that she is going to mold him into a hero who can remove Excalibur from its stone. King Arthur's true intentions are revealed in Camelot and start to emerge in Storybrooke when uses his squire, Grif, to deceive David into believing that Grif had stolen key items, all as part of a plan to turn Storybrooke into the "New Camelot."
Unfortunately, David and Mary Margaret's plan to save Emma and help Lancelot is foiled with Arthur arresting Lancelot and using Guinevere to brainwash David and Mary Margaret into doing his bidding. Lancelot discovers that he is not alone in trying to stop Arthur, as he is joined by another cellmate, Merida. Meanwhile, Hook, with the help of Henry, tries to keep Emma from giving in to Rumplestiltskin's manifestations by spending a romantic day with her. Finally, in Storybrooke, Emma tells a reluctant Gold that she has plans to make him a hero and has found the perfect person to help her do the job: Merida.
In Storybrooke, Emma sends Gold and Merida into the woods so Gold can become the hero, but after seeing how cowardly he is, Merida takes the chipped cup and uses it to bring out his bravery. As Henry convinced Emma to help Violet look for her horse, Regina, Hook, Robin, and Belle sneak into Emma's home and discover not just Excalibur, but the dreamcatcher, where Regina discovers Violet's memories, in which Emma used her to break Henry's heart back in Camelot in order to obtain Henry's teardrop. Regina and Henry both feel betrayed by Emma and shut her out of their life.
When Gold finally realizes that Belle sees him as a coward, Gold brings out his bravery by defeating Merida after the archer turns into a bear. Gold then releases Excalibur and places it at Emma's feet but tells her that he is the hero now. At the same time Emma offers Zelena a deal while the residents discovers Arthur's deception, as well as discovering a message from Merlin with help from Henry.
Using the Promethean Flame, Merlin conjures Excalibur, but Vortigan attacks them, apparently killing Nimue. However, Nimue had also drunk from the grail. Citing her newfound ability to take vengeance, she kills Vortigan, becoming the first Dark One, and breaks the sword into two pieces. Meanwhile, in Camelot, Merlin and Emma set out on a journey to speak with the first Dark One and claim the Promethean Spark; while Zelena double-crosses the heroes and joins forces with Arthur. Zelena imbues Merlin's name to the broken Excalibur, and Arthur uses it to command the suddenly enslaved Merlin to do his bidding.
She claims that all she's done has been for Hook then disappears. While Hook is in search of answers and a way to get Emma's attention, Zelena's pregnancy is suddenly expedited, giving birth shortly after. Believing Emma wants the baby, Regina and Robin rally defences, but she takes Zelena instead. Emma reveals her plan to transfer all dark magic to a vessel, Zelena, to rid the world of it forever. While she is away, Hook and Zelena escape. Zelena reveals to Hook one of Emma's dreamcatchers, enlightening him to his dark predicament.
On her journey, Merida recruits the aid of Mulan and Red, the former an old battle instructor for the princess. When they reach the helm, they are met with opposition from Arthur and Zelena, whom they and members of the clans overpower. Back at the castle, Merida declares she will destroy the helm instead of returning it to the witch. The witch explains that the journey was all a test to ensure that she had the necessary skills to lead the kingdom. The clans unite and Merida is crowned queen. Later, after speaking with the spirit of her father, Merida vows revenge on Arthur, who slayed him.
When he realizes what will happen if he goes through with it, Hook turns Excalibur on the previous Dark Ones and asks Emma to sacrifice him with Excalibur, saving everyone and returning Emma to normal. Emma discovers Gold used the situation to tether the darkness back into himself, leading Emma to blackmail Gold into helping her bring Hook back from the Underworld. Meanwhile, Regina sends Zelena back to Oz, after Zelena attempted to get sole custody of her daughter.
However, as Regina has chosen to stay, Cora's attempts are ineffective, as seeing his daughter choose to stay a hero resolved his unfinished business. With his soul at peace, he is accepted into "a better place" and departs the Underworld after saying goodbye to Regina and Henry. The heroes realize they could potentially rescue all the souls here and continue their quest to find Hook with this in mind. Cora meets with the ruler of the Underworld, Hades, who wishes the heroes gone. He punishes Cora for her failure with an eternity as a miller's daughter once again. Flashbacks show Regina celebrating her birthday with a surprising visit from her mother, Cora.
In the process, Regina convinces Mary Margaret to again become Snow White, the woman who took risks before the original curse. A furious Hades vows to make the outsiders pay by forcing Hook to choose which living souls will stay behind as recompense for the souls they've redeemed. Meanwhile, Henry encounters Cruella, who wants him, in his role as The Author, to resurrect and return her to the world of the living, so that Emma's soul will no longer be branded a murderer's, but he keeps this offer to himself.
Mr. Gold finds Milah, the ex-wife he killed, convincing her to help him and Emma find Hook. However, while Emma rescues Hook, Hades offers Gold the chance to leave in exchange for destroying the boat; Gold blasts Milah out into the River of Lost Souls, hoping to keep the deal secret. Later, when Regina attempts to split Emma's heart in two to revive Hook, she finds a protection spell stopping her. It turns out Hades has chosen Emma Swan, Regina Mills, and Snow White to replace the souls they freed. Also, Hades reveals that he's taken on the debt Gold owes the healer; it turns out Belle is now pregnant. Now, Rumplestiltskin must now work for Hades; otherwise, Hades will take his unborn child.
When Emma catches on to Liam's deception, Hook learns the truth after Captain Silver and his crew reveal what Liam did in the past, which leads to Liam sacrificing himself to save Hook, allowing he and the ship's crew to move on. It is later revealed that the pages Hades wanted have something to do with Zelena. Meanwhile, Henry discovers that the Apprentice is in the Underworld to help guide him in finding the quill, hoping he will make the right decision in lieu of helping Cruella. Later, Cruella makes a move on David while he is impersonating James, only to realize the deception, and she tells David about James' resentment toward him, about being raised by their mother Ruth.
Unfortunately, when they arrive, Zelena discovers that Hades is behind the plot and that her magic is too weak to protect her child, while Belle learns the truth from Gold about his reclaiming his powers and her pregnancy, as well as the contract now with Hades. Zelena gives up her daughter to those who can better protect her, determined to keep Hades from using her to enact the time-travel portal, only to discover his love for her is unchanged. Meanwhile, Snow and David find a way to contact their son, and Henry starts to write stories in his sleep.
Emma has a dream vision that comes true as she, Hook, and Snow attempt to reverse the graveyard spell. When Hook senses a storm brewing, he, Emma, Snow, and Regina go to the woods, where Emma uses her magic to take out the creature borne from the storm. The creature turns out to be a werewolf, who Snow discovers is Ruby/Red Riding Hood, having somehow ended up in the Underworld.
The heroes believe that a kiss from Dorothy's deceased Auntie Em is the solution but, after Hades ruins their plans, Snow suggests to Ruby that her feelings for Dorothy might allow her to break the curse. Meanwhile, David and Snow get antsy after the phonebooth is removed and they have no way to check up on their son. After Hook is able to change the name on Snow's headstone to "David Nolan," Snow is able to leave the Underworld with Ruby and the two head over to Oz, where Ruby is able to free Dorothy.
Gold finds a loophole in his attempt to save Belle and kidnaps Zelena with help from Peter Pan. In the Enchanted Forest in the past, Cora brings Zelena from Oz to save Regina, only to have Cora end their reunion when they discover that they're related, because Cora fears Zelena's presence will derail Regina's future as the next queen.
In the Underworld, Hades, Zelena, her daughter, and the Storybrooke residents return home from the Underworld through a portal made by the fallen clock tower near the Underworld graveyard. The heroes all go through the portal except for Hook, who could not be saved in the end. With Hades' departure, Cruella announces herself as the new ruler of the Underworld.
After he succeeds in reaching Emma, Hook is allowed to move on, only to be rewarded by Zeus with a return to Storybrooke. Arthur stays in the Underworld as he was meant to repair a broken kingdom. Zelena names her daughter Robin in honor of her father during his funeral. Finally, after Moe refused to help bring Belle back from her sleeping curse and Hades chose not to make a deal, Gold takes advantage of the situation by acquiring a piece of the Crystal for a new plan.
After a pep talk from Emma, Henry gives a passionate speech to the people of New York about believing in magic, as their belief will bring it back; he convinces them to use magic wishes in the park fountain to help bring back his family. This opens a portal, bringing the heroes home and proving magic exists. Jekyll gives Snow some of his red serum for Regina, allowing her to separate from the Evil Queen and crush her heart. In the meantime, Gold has met with Mr. Hyde, who promises him information on how to wake Belle in exchange for Storybrooke. Hyde arrives in Storybrooke, along with some of his "friends," threatening the town. Back in New York, The Dragon is confronted by the manifestation of The Evil Queen, who takes his heart and declares war.