When an icy spell is cast on Marian, the residents of Storybrooke place the blame on Elsa, unaware the mysterious woman who runs the town's ice cream parlor has the same powers as Elsa and is trying to frame her.
Emma becomes determined to discover the Snow Queen's plan after discovering she was once her foster mother and Belle searches for the Snow Queen's hideout, as flashbacks show her travel to Arendelle to discover the fate of her mother.
Emma captures the Snow Queen and interrogates her at the sheriff's station and Regina and Robin's relationship grows increasingly complex, as flashbacks detail information about the Snow Queen's life in Arendelle.
Gold interferes with the Snow Queen's plans for his own agenda, as flashbacks show the Snow Queen try to pit Elsa and Anna against each other. Emma turns to Gold for help getting her powers under control.
As the Spell of Shattered Sight approaches Storybrooke, Emma and Elsa search for Anna, Belle and the fairies work on an antidote, and Gold, with a reluctant Hook as his servant, works on an exit strategy.
In the aftermath of the Snow Queen's curse; Emma looks for a portal so Elsa, Anna and Kristoff can return to Arendelle, Regina makes a difficult choice, and Gold's quest for power reaches a dramatic conclusion.
Hook and Belle search for a way to release the fairies from the Sorcerer's hat, Emma, Regina and Henry continue to look for clues that could lead them to the Author, and Gold and Ursula enlist Cruella to join their cause, as flashbacks show their first meeting.
Regina and Henry turn to Marco and Pinocchio for help in their quest to find the Author. Emma worries that Mary Margaret and David are hiding something from her as they remain wary of Cruella and Ursula.
In order to infiltrate the Queens of Darkness as a spy, Regina has to prove that she is still a villain. Meanwhile, Hook asks Belle for an unusual favor, and Henry makes progress on his search for the Author.
Maleficent puts Storybrooke under a sleeping curse in an attempt to steal the page that the Author is trapped inside. Mary Margaret and David struggle with their guilt as flashbacks show them go to extreme lengths to protect their unborn child from darkness.
Regina's plans to head to New York to rescue Robin from Zelena are halted when Cruella kidnaps Henry, as flashbacks show her encounter the Author, who encourages her to stand up to her oppressive mother.
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.