Emma and Regina are about to find out that the portal has opened for a last time only to bring out a frozen evil in Storybrook.

While desperately trying to find her sister Anna, Elsa is startled by Emma and accidentally traps them both inside an ice cave, with the frozen temperature placing Emma's life in peril. Regina, depressed over her likely breakup with Robin Hood, secludes herself away from the town and Henry, which saddens her son. And with the townspeople considering Mary Margaret their leader, she faces her first leadership task in trying to re-start a generator and restore the town’s electricity after Elsa freezes and damages the power lines. Meanwhile, in the Enchanted Forest of the past, Anna tries to teach a meek David to fight Bo Peep, a brutal warlord who is threatening to take his and his mother's farm away if they don’t pay her price.

When an icy spell is cast on Marian, which will ultimately freeze her heart and kill her, the Storybrooke residents place the blame on Elsa. But unbeknownst to anyone, a mysterious woman who runs the town’s ice cream parlor has the same powers as Elsa and is trying to frame her. Emma and David find former Merry Men member Will Scarlet rummaging through Robin Hood’s tent, Regina teams up with Henry to try and discover who the author of the fairy tale book is, Mary Margaret is having trouble balancing her duties as leader of Storybrooke and mother to young Prince Neal, and Hook begins to suspect that Mr. Gold is still in control of the dagger that calls upon him to be the Dark One. Meanwhile, in Arendelle of the past, Elsa and Kristoff set off to stop Hans from attempting to take control of the kingdom.

After Emma asks Hook out on a real first date, Hook visits Mr. Gold and asks for his hand to be reattached so that he can embrace her with both hands. But magic always comes with a price. Henry and Mary Margaret try to offer hope to Regina when she becomes frustrated over not being able to find a cure to save a frozen Marian, and Will Scarlet attempts to break into the Storybrooke library to find a special book. Meanwhile, back in the Fairy Tale Land that was, Rumplestiltskin is after a magical box that the Sorcerer’s apprentice is guarding, and he may use Elsa’s sister Anna to help him get it.

Regina reluctantly teams up with Emma to search for the Snow Queen after Sidney, who is once again Regina's prisoner in the mirror, discovers her whereabouts and agrees to lead her to the location. With Belle babysitting baby Neal, a nervous Mary Margaret and David prepare for their first date night away from their child and find themselves on a mission to track down Will Scarlet, who has escaped from the town jail. Elsa sees Anna in the Storybrooke woods. Young Emma finds herself a kindred spirit when she befriends a girl who, like her, is a runaway orphan.

The race is on to track down the elusive Snow Queen in order to discover what her ultimate end game is for Elsa and the residents of Storybrooke. Unaware that she does not possess the real blade that controls The Dark One, Belle attempts to use it to get her reluctant husband to show her where the Snow Queen is hiding. Belle travels to Arendelle and, with Anna's help, seeks out Grand Pabbie to help her regain her lost memories in order to discover the fate of her mother.

Emma captures the Snow Queen and interrogates her at the sheriff’s station. Regina and Robin Hood’s relationship grows increasingly complex as they struggle to find a way to save his dying wife. Emma begins to see what she missed out on by not growing up and being a family with Snow and Charming. Henry begins his after-school job in Gold’s shop while trying to help Regina find a clue to the identity of the author of the storybook. The history of the Snow Queen is revealed.

In Arendelle, when the Snow Queen tries to pit Elsa and Anna against each other and it proves more difficult than she anticipates, she takes drastic measures. Meanwhile, in Storybrooke Emma’s powers are out of control and her fear of hurting loved ones pushes her away from everyone she cares about. In her confusion, Emma turns to Gold for help getting her powers under control. Gold tells her about a way to get rid of her powers altogether and Hook tries to put a stop to it. Meanwhile, Regina struggles with her plan to find the author of the storybook until her quest takes an unexpected turn. Robin Hood recruits Will Scarlet to assist him on a mission and Mary Margaret and David search for Emma.

When the Snow Queen tries to pit Elsa and Anna against each other, it proves more difficult than she anticipated. Emma’s powers are out of control and her fear of hurting loved ones pushes her away from everyone she cares about. Regina struggles with her plan to find the author of the storybook until her quest takes an unexpected turn. Robin Hood recruits Will Scarlet to assist him on a mission. Mary Margaret and David search for Emma.

As the Spell of Shattered Sight approaches Storybrooke, Mary Margaret and David rally the residents to prepare for the curse while Belle and the fairies work together on an antidote. Gold, with Hook as his reluctant servant, sets about an exit strategy of his own. Regina and Robin Hood ready themselves for the worst while, with the help of a locator spell, Emma and Elsa search desperately for Anna. In Arendelle, Anna and Kristoff awaken to find that their kingdom is once again in danger.

Storybrooke is in a state of chaos with all the residents under the Snow Queen’s Spell of Shattered Sight at each other’s throats. Emma and Elsa race against the clock to free themselves of the ribbons and take down the Snow Queen and her curse. David can only watch when Regina clashes with Mary Margaret in an epic battle. Meanwhile, Gold gathers Belle and Henry as he prepares to leave town forever, and Will Scarlet looks to square his tab with Hook. Kristoff’s thick-headedness leads Anna to a heartwarming discovery.

In the aftermath of the Snow Queen’s spell, our heroes try to pick up the pieces and Regina has to make a difficult choice. Hook’s fate hangs in the balance as Gold’s quest for power threatens everything he holds dear. And, in the Enchanted Forest flashback, an intrusion during Belle's stay at Rumplestiltskin's dark castle will wreak havoc in both the past and the future.

With Gold banished from town, the residents of Storybrooke attempt to resume their normal lives. Hook and Belle search for a way to release the fairies from the Sorcerer's hat, while Emma, Henry and Regina continue to look for clues that could lead them to the Author. But when a terrifying darkness descends on the town, Emma and Regina are forced to confront the true nature of evil. Meanwhile, in New York, Gold and Ursula enlist Cruella De Vil to join their cause.

David and Mary Margaret suspect Cruella and Ursula have come to Storybrooke looking for something more than their own happy endings - something that threatens to reveal a secret they thought was long buried. Emma begins her own investigation of Cruella and Ursula, but she can't shake the feeling that her friends and family are keeping something from her. Regina and Henry continue their search for the Author, turning to Pinocchio and Marco in the hope Pinocchio might remember a clue that will help them. Meanwhile, in a flashback to Fairy Tale Land, Snow and Charming cross paths with the Queens of Darkness as the threat of the Evil Queen's Dark Curse hangs over all of them.

In order to infiltrate the Queens of Darkness as a spy for the heroes, Regina must prove she's still willing to get her hands dirty. Meanwhile, Emma, David and Mary Margaret scramble to keep tabs on their undercover operative. Hook requests an unusual favor from Belle as Henry makes progress on his search for the Author. In a Fairy Tale Land flashback, Regina befriends Maleficent and helps her to rekindle her lost spark.

Hook leverages his complicated history with Ursula to find out what she knows about Gold's endgame. Gold and the Queens of Darkness torture August for information about the Author as Emma, Mary Margaret and David race to find them. Regina grows concerned for Robin Hood's safety while she struggles to maintain her cover with the villains. In a Fairy Tale Land flashback, when a restless young Ursula enlists Hook's help to run away from home, she soon learns it isn't wise to trust a pirate.

Hook tells Emma that her fate is at stake in Gold's plan while Regina leads the villains on a wild goose chase. Henry makes a breakthrough in his search to find the Author, but Mary Margaret and David need a moment to reconsider the best course of action. In a Fairy Tale Land flashback, Snow and Charming search for a way to ensure their child will grow-up to be a hero. When a traveling peddler directs them to visit a kindly old hermit, Snow and Charming are presented with a choice that could secure their child's goodness, but at a price that will haunt them for years to come on.

Emma is still reeling after learning the truth of her parents' history with Maleficent, but she must focus on finding the Author, who is running loose in Storybrooke, before Gold does. When Gold's quest for his happy ending grows more urgent, he blackmails Regina into helping him. In a Fairy Tale Land flashback, Robin Hood learns what it means to be an honorable thief when he accepts a proposition by Rumpelstiltskin to travel to Oz to steal a valuable magic elixir from the Wicked Witch.

In fictional 1920s England, viewers meet a young Cruella, whose oppressive mother uses her Dalmatians to terrorize her daughter. Cruella is confined to her mother's attic until a mysterious stranger arrives and empowers her to challenge her captor. In Storybrooke, Regina gains leverage to keep Gold from interfering with her plan to rescue Robin, but her trip to New York takes the backseat when she and Emma learn that Cruella has kidnapped Henry.

Emma's potential for darkness is looming over everyone, but when Emma realizes Maleficent's daughter Lily is in fact her closest friend from her foster care days, she resolves to find Lily and reunite her with her mother. Regina joins forces with Emma and together they set out to track down Lily and to warn Robin about Zelena. However, neither of them is prepared for the harsh realities they'll encounter in the outside world. Meanwhile, in Storybrooke, Gold faces a crisis involving Belle. In a foster care flashback, things are looking up for young Emma with her new family until Lily's appearance threatens to destabilize everything.

Emma returns to Storybrooke to reunite Lily with Maleficent while Regina and Robin struggle to cope with the implications of Zelena's pregnancy. When Gold's health takes a turn for the worse, Isaac looks to a new ally for help procuring the magic ink he needs to re-write history. In a Fairy Tale Land flashback, Cora returns from Wonderland to beg Regina's forgiveness on the anniversary of Daniel's murder. Cora vows to help her daughter find true love, but Regina remains suspicious of her mother's intentions.

The Author proves to be a formidable wild card and forges an alliance with Gold. Emma, her parents, Hook and Regina scramble to stop them, but when Gold and the Author turn the tables on heroes and villains alike, the prospect of any happy outcome appears worlds away. Henry discovers he has big shoes to fill as he steps up to save his family before the story's final page is turned. It's a race to the finish, and everything culminates with a shocking twist that will leave the residents of Storybrooke reeling.

The Author proves to be a formidable wild card and forges an alliance with Gold. Emma, her parents, Hook and Regina scramble to stop them, but when Gold and the Author turn the tables on heroes and villains alike, the prospect of any happy outcome appears worlds away. Henry discovers he has big shoes to fill as he steps up to save his family before the story's final page is turned. It's a race to the finish, and everything culminates with a shocking twist that will leave the residents of Storybrooke reeling.