Emma and Regina formulate a plan to trap the Evil Queen in a prison of their own making, while Snow and David adjust to life without each other. As Henry nervously prepares to take Violet to the school dance, the Evil Queen impersonates Regina to give him some advice that could lead him down a dark path. Meanwhile, Zelena agrees to help Belle, and together they enlist Aladdin to steal a magical object from Mr. Gold that could protect Belle and her unborn child from him forever.
The forest is filled with mirrors, with the "O" mirror: The World Behind the Mirror showing off the blue mist.
In the present day, Snow and David are finding themselves dealing with living without each other as long as their hearts are cursed, leaving one in sleep and the other awake, and Snow and Henry are aware that the Evil Queen is watching, leading to Snow smashing a mirror as they catch on. Unfortunately at this point there is nothing that even Emma, Henry, or Regina can't do, but they believe that The Dragon might be their answer to stopping The Evil Queen. With no luck finding The Dragon, Regina comes up a solution, which is using a mirror to trap her other half. At the beach, Henry, acting as bait, confronted The Evil Queen to remind her that he won't forget what she done to his grandparents. After they sent him away, Emma and Regina appeared and ready to send The Evil Queen to another world through the Mirror, but The Evil Queen, who shared the same mind as Regina, had the real mirror and sends Regina and Emma to the other side, then breaks the mirror to keep the women trapped inside. Inside the trapped universe, Emma looked for Regina and discovers that she can see Storybrooke through the mirror but nobody can hear them. Regina comes to and believes that the person who can reach them is Henry. However, The Evil Queen has taken Regina's place by fooling Henry to let him know that The Evil Queen was banished.
Meanwhile, Belle enlisted Zelena's help to break into Gold’s Pawn Shop so she can escape Storybrooke. Zelena isn’t interested in helping her but Belle says they both know what it’s like to care about people who let them down. Realizing that Zelena needs the sorcerer’s wand, Belle and Zelena go talk to Aladdin and Jasmine into helping them. Although Jasmine says it’s not Aladdin's business to be involved, Zelena says it’s his fault because thanks to Aladdin, Gold has now acquired the Fates shears. At the same time Gold catches on to The Evil Queen's masquerading as Regina, and refused her advances. The Evil Queen then asks Gold for a item called the hammer of Hephaestus, which gives magic to those without it, explaining that she wants it for Henry. As he gives the hammer to the Evil Queen, Gold asks what she has to offer him, only to point out they're on the same team, as he pushed her away. The disappearance of Emma has Hook suspicious, and finds himself attacked by The Evil Queen after he finds Emma’s phone on the beach.
Inside the mirrors, Emma and Regina are looking for Henry in the mirrors, this after Emma remembers Henry will be at Granny’s to meet Violet. At Granny's, Henry sits alone at a table, waiting for Violet, then looks in the mirror to see his appearance. As both Emma and Regina sees Henry, they almost get his attention until they see The Evil Queen (pretending to be Regina) show up. Henry tells the fake Regina that he doesn’t think he’s good enough for Violet, but she tells Henry he’s a prince and should act like one. After Henry glanced at her carefully, Violet shows up and Henry walks over and hands her the flower that "Regina" gave him, then tells Violet that was The Evil Queen after he caught on to the "lecture" she made about his posture, which he knows as her recurring theme. Using a ruse to help Henry search for Emma and Regina, Violet makes an excuse about another dress and they leave. Back in the mirror, Regina is worried and says Henry doesn’t stand a chance against her. Suddenly, the women are shocked to see The Dragon inside with them as a prisoner as well. He tells Regina she let the bad side out and that caused this and tells Regina she needs balance. He says he found a back door out of the mirror world. En route, the Dragon leads the women to Sydney's place and tells them he was putting together a way to repair the portal, but tells Emma he can't break her parents' curse however. As they work on the portal. Henry arrived to the vault to contact the mirror when The Evil Queen shows up now that he is aware of her plan. The Evil Queen then tempts Henry to become part of her future but when he refused, The Evil Queen takes out The Dragon's heart and use it to turn The Dragon into a Dragon in front of Emma and Regina to kill them. The Evil Queen then tempts Henry to kill The Dragon with the Hammer but he defied her and uses the Hammer to smash the mirror and frees Emma and Regina. After they're released, The Evil Queen is stunned by Henry standing up for himself but as she was going to use magic on them, Hook stops her but vows revenge. Later on that night, Henry and Violet finally have the dance and Emma and Regina watched.
In between the events, Aladdin breaks into Gold’s shop looking for the wand. He finds Gold at the spinning wheel spinning gold, and is quick to hide from him, allowing Aladdin to find the wand, and later on, show Jasmine the lamp, where he hope to find out who took the Genie's place. Unfortunately for Belle and Zelena, they weren't as lucky; Gold takes back the wand from Zelena, then used the gold bracelet he spun at the shop to place on Belle so he can track her, not knowing that he forgot about what Zelena did to him back in New York City as she restored the heart attacks to remind him of the deal they made to keep Gold alive after he tried to choke her. Later on back at the shop, both Gold and The Evil Queen, upset over their latest defeats, agreed to team up to seek vengeance, and as they have more tepid kissing, Gold asks The Evil Queen to help him kill the one thing that stands in his way: Zelena.