When Emma finds Elsa in an ice cave she triggered, her life is in danger when Elsa traps her in with her. Meanwhile, in the Enchanted Forest of the past, Anna helps teach a younger David to fight a warlord named Bo Peep.
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.
Hook asks Gold for his hand to be reattached for a first date with Emma. Henry and Mary Margaret try to help Regina when she becomes frustrated over not being able to find a cure for a frozen Marian. Back in the Fairy Tale Land that was, Rumplestiltskin uses Anna to acquire a magical box from the Sorcerer's apprentice.
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, and Elsa sees Anna in the Storybrooke woods. Meanwhile, back in the past, young Emma finds herself a kindred spirit when she befriends a girl who, like ...
Belle attempts to use Rumplestiltskins dagger to find out where the Snow Queen is hiding. Hook and Emma search for answers about the snow queen. Back in fairytale land of the past Anna returns home from her time in the enchanted forest but doesn't know what to tell her sister about what she found out.
In Arendelle, when the Snow Queen tries to pit Elsa and Anna against each other and when 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 ...
Elsa and Emma find Anna. The fairies attempt to protect everyone against the curse but are trapped by Hook before they can succeed. Everyone in Storybrooke locks themselves up and waits for the curse to hit.
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.