Elsa doesn't want anyone to leave Storybrooke until she finds her sister. She forms an ice wall around the town. As she unleashes her power, Henry receives a message from Regina saying she doesn't want to see him. Emma says it's because she's nursing a broken heart. Their conversation is cut short when the entire town suffers a blackout. David and Emma investigate to find a giant snow wall. It took down all the power lines. Hook says the wall envelops the entire town.
Emma finds Elsa hiding amongst the ice. She learns about her search for Anna. Elsa gets spooked when David and Hook approach. She causes an ice cavern to form. Emma and Elsa are trapped inside. David knows that only magic will be able to help them break though the icy prison. Inside, Elsa orders Emma to tell David and Hook to go find Anna. They need to do so before she freezes the entire town and everyone in it.
In town, the people nominate Mary Margaret to get the electricity back up and running. After all, Regina is MIA and it was her curse that caused all their lives to take a turn. Back at the ice fortress, Emma realizes that Elsa can't control her powers. She passes out. David rushes to Mr. Gold's shop, as that's where Elsa found the necklace that belongs to her sister. He recognizes the piece of jewelry the moment he sees the picture. He knows exactly who Anna is.
Many years ago in the Enchanted Forest, Anna finds David. She got his name from Kristoff. As for her name, she says it's Joan for his safety. Speaking of staying safe, David suggests she retire to his barn as a carriage approaches. He says the person riding in it is no one she wants to know. They call her Bo Peep, and she wants extortion payment from David and his mother. She has powerful, magical shepherd's crook and an army to help her get what she wants. Anna encourages David to fight back. She can teach him how to use a sword.
David tells a story about how his parents always used to fight. One day, his hard-drinking father promised he would be better for their boy. He would return in two weeks a better man. That didn't happen. One the 14th day, his dad went on another bender and was killed as a result of it. Anna believes that just because David had a weak father, it doesn't mean he is the same way. Bo Peep later tells David that she has branded Anna to be one of her sheep.
David manages to defeat Bo Peep and her men in a sword battle. He uses the shepherd's crook to find Anna in a stable. He returns the necklace that Bo Peep stole. He lets Anna know that the reason he fought an impossible battle is because he couldn't live with himself if he was trapped in a life he didn't want.
In present day Storybrooke, David pays a visit to the present day Bo Peep in her butcher's shop. He tells Hook to fetch her shepherd's crook. Emma is freezing to death. David lets Elsa know that even though she feels trapped in a battle she can't win, she has to fight. She has to live. Elsa knows this is something Anna would say. David confirms that he knew her sister a long time ago. She helped him become the man he is today. She saved his life. Now he needs her to save Emma.
Elsa uses her powers to melt a hole through the ice cave. David and Hook are able to get to Emma. She's weak, but alive. David tells Elsa that what he said was true. Anna helped him, and now he's going to help her. They are going to find her sister. Elsa is upset because she lost Anna's necklace in the ice cave. On the bright side, they still have Bo Peep's shepherd's crook. In other news, at the town's power center, Mary Margaret manages to get the electricity up and running all while holding a hungry baby in her arms. Not a bad first day's work for the new mayor of Storybrooke.
In the Enchanted Forest of the past, David's mother lets Anna know that there's a powerful wizard who may be the person her parents were seeking. She doesn't like to say his name, but she does write it down for her. David gives Anna his horse for her journey. Perhaps the two of them will meet again someday. Until then, Anna is off to see the wizard whose name is on the paper David's mom slipped her. It reads: Rumplestiltskin.
Elsa can't see anything with the shepherd's crook, but everyone can hear a heartbeat. They may not know where Anna is, but they do know she's alive. David introduces Mary Margaret to Elsa. She clues her in on the plan to find Anna because the one thing this family does not do is give up. Henry takes these words to heart. He goes to see his mother to let her know that he's not going to give up on her. Regina opens the door and gives Henry a hug they both need.
Emma is impressed at how cool the ice wall is-pun intended. Elsa guesses that it's probably a good thing that she's only one who has such powers. She tries to take down the ice wall. For some reason, she can't do it. Back in town, Leroy gets a scoop of ice cream from the lady who owns the Any Given Sundae parlor. The power outage didn't affect her inventory at all. With a wave of her hand, the woman turns a container of milk into ice cream. When she leans back, ice spreads in a tentacle pattern along the wall. Perhaps Elsa isn't the only one with such chilling powers.