Regina deals with the repercussions of losing Robin after Emma brings his wife from the past, and turns to an friend for help. Meanwhile, a mysterious ice princess arrives in Storybrooke and unleashes chaos. In the past in the kingdom of Arendelle, Elsa and Anna discover that their parents were killed trying to find a cure for Elsa's condition, and Anna sets out to find the same cure.
Elsa traps Storybrooke within a wall of ice while trying to find Anna, but is unable to release them... and puts Emma's life in danger. Meanwhile, when the power goes out, the townspeople insist that Mary Margaret deal with the crisis. And in the past, Anna visits David and helps him learn how to fight so that he can defeat the dreaded warlord Bo Peep.
Marian falls under a freezing curse and the townspeople believe that Elsa is responsible. When Emma and David go to Robin's camp to look for clues, they find Will Scarlet, who leads them to the culprit. Meanwhile, in the Arendelle of the past, Elsa and Kristoff go to find the urn that Hans plans to use to imprison Elsa, and encounter the Snow Queen.
To prepare for his first real date with Emma, Hook blackmails Gold into restoring his left hand. However, the pawnbroker warns that all magic comes with a price. Meanwhile, Will tries to steal a book from the library. In the Enchanted Forest of the past, Anna has no choice but to agree to do a favor for Rumplestiltskin return for knowledge of why her parents traveled to see the Dark One.
Emma tries to convince a reluctant Regina to help her find the Snow Queen, only to discover that Regina is lying to her about Sidney's whereabouts. Meanwhile, David convinces Mary Margaret to go on a date, but the date turns into a hunt when Will escapes his jail cell. In the past, Emma befriends another young orphan who isn't all that she seems.
The race is on to track down the elusive Snow Queen, who was once a foster mother to a young Emma - whose memories of this event have been erased - in order to discover what her ultimate end game is for Elsa and the residents of Storybrooke, and 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. Meanwhile, back in the past, 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.