When the Candy Killer attacks, Ivy will have to risk what remains of her family, while Jacinda and Henry grow closer and Roni questions her relationship with Samdi. Meanwhile, Drizella faces an unthinkable challenge in her attempt to join the Witch's Coven.

Cinderella joins forces with a new friend; Jacinda tries to protect Lucy's community garden; Lucy tries to convince Henry that Victoria is after more than just a plot of land; Victoria makes a discovery that could alter everyone's fate.

In flashbacks, Ruby and Mulan find themselves in Oz, where they meet Dorothy. After the three witness Zelena’s return to Oz, they look for a way to defeat her once and for all. However, Dorothy mysteriously disappears, and Ruby’s search for her new friend lands her in the Underworld. Reunited with the heroes, Ruby teams up with Emma, Regina and Snow to continue looking for Dorothy. Meanwhile, Snow and David struggle with not being able to be with their son, Neal, and devise a plan so that one of them can escape the Underworld.

Tana seeks help from a traveling soothsayer, the iconic Dr. Facilier, in an attempt to save her kingdom. But when it’s revealed that he has an ulterior motive she’s forced to take matters into her own hands. In Hyperion Heights, Sabine and Jacinda take on a risky business venture, but the strength of their friendship is tested when Victoria interferes with their plans. Meanwhile, Ivy recruits Henry to investigate Victoria, and Roni makes a discovery that could change her relationship with Henry forever. Rogers uncovers a crucial clue in his search for Eloise Gardener.

Zelena and Arthur journey to DunBroch on a mission to retrieve an enchanted relic that will provide the advantage they need to vanquish Emma and our heroes. Their path will cross with Merida’s, who is on a journey of her own to pay a debt that her father, King Fergus, owed to the Witch when he died. Merida enlists the help of two friends, Mulan and Ruby, but, in order to satisfy the Witch and save DunBroch, she first must discover the identity of the knight who killed her father. In flashbacks, Merida learns about bravery and honor as she trains for combat and rides alongside Fergus into the infamous battle that claims his life.

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.

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 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.

Henry leaves Storybrooke in search of his own story. Years later in another realm, he encounters a troubled Cinderella, changing the trajectory of his quest forever. When Cinderella's evil step-mother, Lady Tremaine, poses a threat, Henry discovers that following his heart will require him to make more difficult choices than he ever could have imagined. Years later, a young Lucy finds a disillusioned Henry at his home in Seattle, determined to make him remember his true self in order to defeat the curse afflicting the fairytale characters of "Hyperion Heights."

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.

In pursuit of revenge, Hook seeks a dark and powerful magic, but an encounter with Rapunzel could alter his fate forever. Meanwhile, in Hyperion Heights, Ivy’s plot to take down Victoria intensifies and has unexpected consequences for Jacinda and Lucy. Rogers enlists Henry and Tilly’s help in his ongoing quest to find the missing Eloise Gardner, but what he discovers isn’t what meets the eye.

David, Emma and Mr. Gold try to protect Mary Margaret from a vengeful Regina; a man and his son find their way into Storybrooke.

In a Camelot flashback, a chance encounter with Merlin, David, Hook and Belle gives Merida new hope in her quest to save her brothers from the usurping clans of DunBroch. Unwilling to leave anything up to fate, Merida brings Belle along on a dangerous journey that culminates with an invaluable lesson in bravery. In Storybrooke, Regina, Mary Margaret and David discover the spell that would allow one of Merlin’s chosen to communicate with him, but when Arthur fails to reach the missing sorcerer the heroes grow suspicious. Meanwhile, Emma commands Merida to kill Belle in hopes of forcing Mr. Gold’s heroic transformation. With Merida unable to disobey Emma’s orders.

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.

After receiving a cryptic warning from Lancelot about Arthur's intentions, Mary Margaret realizes Arthur may be the heroes' biggest threat, but when she is unable to convince David of the danger, she takes matters into her own hands. Meanwhile, Hook's unwavering love for Emma provides a glimmer of hope in her struggle against the unrelenting voice of Rumplestiltskin. In a Camelot flashback, Guinevere senses that Arthur is losing his way, consumed by his obsession with making Excalibur whole, so she sets out with Lancelot on her own quest into the heart of darkness. In Storybrooke, Dark Emma unleashes a secret weapon in the next phase of her plan to find the brave soul she needs to draw Excalibur from the stone.

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.

In an attempt to prevent a distressed Alice from running away, Henry and Ella follow her into Wonderland. Once there, Henry realizes that Ella has a surprising connection to this strange world. In Hyperion Heights, Jacinda reconnects with an old friend in a last ditch effort to regain custody of Lucy, but her decision to enlist outside help could put a strain on her burgeoning relationship with Henry.

Victoria strikes a deal with Weaver in an attempt to free herself from jail and wake Anastasia, but the cost of saving one life could mean the loss of another. In a flashback, we learn Lady Tremaine’s surprising connection to another classic fairytale when Mother Gothel offers to help her family. Meanwhile, Jacinda and Nick share an exchange that could alter her future with Henry.

On the day of Tiana’s coronation, a confrontation with Dr. Facilier compels her to take a trip through the Bayou, where a surprising encounter changes her life and the hunt for an alligator takes a dark turn. In Hyperion Heights, Sabine reconnects with an old friend whose plans could jeopardize her culinary dreams. Meanwhile, Rogers and Weaver investigate a Blind Witch, leading them to a shocking discovery about The Coven.

Rogers strikes a deal with Eloise despite Tilly’s fair warning, while Ivy struggles to find herself after Victoria’s death. Meanwhile, in a faraway realm, Hook confronts Captain Ahab over a legendary magical talisman which can free Alice, only to learn that his quest may have unintended consequences.

Henry grapples with an important decision when a job prospect in New York threatens to take him away from Jacinda and Lucy, but a revelation in the case of The Candy Killer could make it even harder to leave Hyperion Heights. Meanwhile, Margot confides in Tilly, and in a flashback, Hook helps Henry find a way to prove himself to Ella.

As Regina tries to refrain from using her magic in order to regain Henry's trust, she starts seeing a ghost from her past; Mary Margaret and Emma find a survivor from an Ogre massacre; Regina struggles to learn the dark arts.

In Camelot, Merlin spearheads a mission to reunite the dagger with Excalibur so he can use the weapon to save Emma from the darkness threatening her soul. With Zelena in tow, Hook, Mary Margaret, David, Regina and Robin steal into Arthur’s castle to take the broken sword from the maniacal king. Meanwhile, Merlin brings Emma along on a journey to confront his ancient nemesis and retrieve the sacred spark he’ll need to reforge Excalibur. Both parties are tested, but one suffers a blow that could derail the entire operation. In a flashback to long before the Age of Arthur, young Merlin finds purpose after he is blessed with magic and immortality, but when he falls in love with a young refugee named Nimue, everything changes for Merlin, as their romance starts a chain of events that touches every one of our present day heroes.

In a Camelot flashback, Hook becomes a Dark One and his lust for revenge against Rumplestiltskin is reignited. When Emma and Hook disagree about their best course of action, the final pieces of the puzzle are revealed as events in Camelot catch up to the present and we witness a charged confrontation between the forces of light and dark that sends our heroes on a collision course with destiny. Meanwhile, in Storybrooke, Hook’s centuries old lust for revenge against Gold puts both of their fates in jeopardy while Emma’s love faces the ultimate test as she tries to convince Hook to turn away from the darkness before she, Mary Margaret, David and Regina embark on a new mission as an unsuspected evil is released.

In Underbrooke, Hook questions whether he is worthy of forgiveness after meeting his brother Liam. In the past, Liam makes a deal of his own to save himself and his brother... at the cost of a ship's worth of men. Meanwhile, Henry meets the Apprentice and learns of his true power.