As our heroes set out to stop Hyde, Emma develops a mysterious side effect, and Storybrooke becomes a haven for refugees from the Land of Untold Stories. Meanwhile, Regina and Zelena embrace their newfound sisterhood by becoming roommates, while Rumple tries to free Belle from the sleeping Curse with the help of a stranger. In flashback, Jafar confronts an afflicted Aladdin in Agrabah, and a secret about the Savior is revealed.
When a mysterious man from the Land of Untold Stories, who has a past with the Evil Queen, arrives in Storybrooke, David and Snow work together with Regina to neutralize the threat. Belle seeks Hook's help finding a safe place to hide away from her husband, Mr. Gold. The Evil Queen continues to try to win Zelena over to her side, while Emma resumes her therapy sessions with Archie and shares her terrifying vision of the future.
As Storybrooke continues to welcome the new arrivals from the Land of Untold Stories, families, friends and enemies are reunited once again. When Cinderella searches for her step-family, intent on settling their unfinished business, Emma, Hook and Henry scramble to help her before it's too late. Meanwhile, Regina attempts to bribe Mr. Hyde for information about how to defeat the Evil Queen, and Snow helps Dr. Jekyll find a laboratory for his work.
The Evil Queen and Hyde continue on their quest to steal Dr. Jekyll's serum; Snow looks forward to her first day back as a school teacher; and while Emma looks forward to Hook moving in with her, Hook finds himself trying to protect Belle from Mr. Gold, who has made sure she can't leave the confines of the pirate ship.
Princess Jasmine recruits Aladdin to help her recover a secret weapon capable of breaking Jafar's hold on the Sultan and saving the city from ruin. In Storybrooke, the Evil Queen tricks Hook and the Charmings and forces Emma to reveal her secret in an effort to divide the family.
Emma tries to convince Aladdin to work with Jasmine to help Agrabah, while Regina teams up with Snow and David to free Archie from Zelena. Meanwhile, in the past, Hook finds himself kidnapped by the mysterious Captain Nemo and held captive aboard his submarine, the Nautilus.
In Storybrooke, the Evil Queen threatens to destroy the town and everyone in it unless Snow and David surrender their hearts. As Emma, Hook, and Henry prepare to defend Storybrooke, Snow, David, and Regina search for a magical sapling created by the first spark of true love.
Emma and Regina formulate a plan to trap the Evil Queen in a prison of their own making, while Snow and David adjust to life without each other. Meanwhile, Zelena agrees to help Belle, and together they enlist Aladdin to steal a magical object from Mr. Gold that could protect Belle and her unborn child from him forever.
Gold tells the Evil Queen she must kill Zelena, and the Queen makes a decision that will change her relationship with her sister forever. When Belle discovers Gold's plans for their son, she convinces Hook and Emma to help her steal squid ink that can immobilize him. Meanwhile, Jasmine finds a genie-less lamp that she hopes to use to save Agrabah.
When she learns the heroes possess a weapon capable of defeating her, the Evil Queen steals Aladdin's magic lamp from Jasmine and makes a wish that could sideline the Savior forever. Unwilling to wake Snow while Emma is missing, David works with Hook and Henry to hold the Evil Queen at bay in Storybrooke.
With Snow still asleep in Storybrooke, David and Hook race to stop Gideon before he can confront Emma. Meanwhile, Regina struggles with the realization that everyone, even Robin, is better off in the alternate world where the Evil Queen was defeated. And when Emma inspires a familiar face to help her and Regina return home, she discovers the power to change her fate.
Before Hook takes the next step in his relationship with Emma, he wants to make sure David sees him as more than just a pirate. When David asks Hook to help him uncover the truth about his father's death, Hook agrees. Meanwhile, Regina works to acclimate Robin to life in Storybrooke, but soon discovers he has a dark side that makes the task much more complicated than she anticipated.
When Gideon resumes his mission to kill Emma and become the Savior, Gold steps in to ensure that the use of dark magic does not poison his son. Meanwhile, Robin proves willing to ally himself with anyone offering the possibility of escape from Regina and Storybrooke. Hook gathers the courage to come clean to Emma, but not before she discovers he's been keeping a secret.
Believing there isn't room in Storybrooke for both her and Regina, the Evil Queen sets out to eliminate her other half. Hook, determined to make things work with Emma, turns to his old friend Captain Nemo for advice, but Gideon torpedoes the plan before he's able to set things right.
When Hook finds himself trapped in another realm along with the Nautilus and her crew, he races to return to Emma before Gideon can execute the rest of his plan. In Storybrooke, Regina and Snow take Emma out to get her mind off Hook's disappearance. And in a flashback to Agrabah, Jasmine befriends Ariel, and together they set out to locate Prince Eric as the threat from Jafar intensifies.
Gold and Belle convince Emma to help Gideon, explaining that together they can stop the Black Fairy. Henry experiences a disorienting shift in his powers that forces Regina to seek counsel from the previous Author. Meanwhile, in Fairy Tale Land, Hook attempts to win the assistance of an old adversary by betting his most prized possession on a game of cards. And, in a flashback, the Black Fairy tortures young Gideon in hopes of molding him into the perfect apprentice.
Trapped in Neverland, Hook aligns himself with Tiger Lily, hoping to find a way back to Emma. In Storybook, Regina works to break the sleeping curse that David and Snow are under, and Gold denies The Black Fairy, which brings the two of them to a fearsome impasse.
Zelena decides to take on the Black Fairy and put a stop to her, once and for all, against Regina's wishes, and the Charmings disagree over Emma and Hook's wedding plans.
After Rumple's mother learns from his fairy godmother that his destiny is prophesized, she does everything in her power to keep it from happening. Meanwhile, in Storybrooke, Rumple faces a similar delimma.
In flashback, Snow and Charming make a special wish that Emma will be protected. The result of their wish has the whole kingdom bursting into song which infuriates the Evil Queen. Meanwhile in Storybrooke, the Black Fairy announces her plans to unleash another curse on the town while Emma and Hook prepare for their wedding.
Henry wakes up in a strangely changed Storybrooke where Emma is a mental patient and the rest of his family has disappeared.
Emma regains her memory but discovers that the Black Fairy has set the perfect trap for her. Meanwhile, the Evil Queen makes the ultimate sacrifice to save her former kingdom, and Gold is forced to choose between Good and Evil.