The four geysers from The Wizard of Oz's Palace fires up the series' title.
In the Characters' Past
While travelling down a road, a woodcutter and his wife notices a tornado coming. After it disappears, the two see a basket and it falls to the ground, discovers a baby girl inside. As they pick it up, a tree branch is about to fall on them but the baby makes it move out of the way, saving the couple. The woodcutter believes there is something that is not right about the baby, but his wife believes that she might be special and wants to keep the child, as they head for a place that is revealed to be the Emerald City of Oz. Fast forward to the years before the first curse, as Zelena shaves her father perfectly until she gives him a bloody nick, leading him to reveal to her that she is not his daughter and is nothing but a "witch." Zelena, who then lashes out at him for being a drunk, decides to go to the Wizard to find out the truth about her past, where upon her entry into the chamber she finds a curtain that covers a shadowy Wizard. He then asks her to look into a visionary portal and she discovers her mother Cora abandoning Zelena because she couldn't give her the one thing she wanted, royalty. But as she continues to watch, the Wizard tells her that Cora would later groom her younger sister Regina for royalty and would be later trained in sorcery by Rumplestiltskin. Zelena is then given a pair of silver slippers by the Wizard. When she clicks her heels three times they will bring her wherever she wants to go, but in return he wants something of Rumplestiltskin's, and then cautions Zelena that her actions will make her green with envy. She then uses it to take her to the Enchanted Forest and Rumplestiltskin.
Zelena feels that with Rumplestiltskin teaching her, she now feels happy with him. Unfortunately, this would all change when he skips out on a feast that she made for him in order to continue teaching Regina, making her more envious than ever. This prompts her enter to Regina's bedroom to kill her with a blade, only to find out that she was tricked by Rumplestiltskin (disguised as Regina). Zelena discovers that she had failed his test because the curse demands giving up the thing you love most, and that was her love for Rumplestiltskin, who then responds "It's OK. I have that effect on women." She also discovers that Rumplestiltskin has already trained Regina to become powerful, and Zelena's throat turns green. Rumplestilskin then tells Zelena that unless she can take him to a land without magic, Regina has the job. Zelena says bitterly that she could have, thanks to her slippers, but tells him its too late for that, since he had already chosen Regina. Then, Zelena tells Rumplestilskin that the only way he could get the slippers from her was to kill her, only to teleport away when he tries, saying "You shouldn't have taught me all your tricks. And the next time, you will choose me." Then, Zelena uses her slippers to disappear back into Oz.
Back in Oz, Zelena demands that the Wizard help her to travel back in time to stop Cora from abandoning her, but he claims that it's impossible, even for him. Suspicious, she uses her power to bring the curtain down. It turns out that the Wizard is none other than Walsh (Emma's boyfriend and ex-fiance), a circus barker from Kansas. Walsh says he does not have magic, but he collects it. Zelena decides that she has no use for him, but what she could use is a trained circus animal. And after seeing a flying monkey poster, she drags Walsh and transforms him into one to do her bidding. Zelena then uses the magic viewer in the floor to watch Rumplestilskin train Regina, even as she turns green with envy and wicked as ever, vowing that by the time she was done, Regina would have never even been born.
At Neal/Baelfire's funeral, Everyone takes turns at burying his casket, while back at the farm Zelena taunts Gold about losing his son. Later on at Granny's, Emma makes bulls eyes and scores perfectly while playing darts which Hook suspects is her way to exact revenge on Zelena. Hook then tells Emma that Hook wants to spend some time with Henry as way to make up for Neal's loss, and Emma lets Henry go with Hook. Meanwhile, Tinker Bell notices the crest on Robin Hood's arm and asks Regina if it's the man from her prophecy, which Regina confirms, but when Robin comes over to talk, Regina changes the subject. Unfortunately, this gathering at Granny's is interrupted by Zelena, who bursts into the diner to confront Regina. She tells her that they are half-sisters and that Cora is their mother, then challenges her to a duel and sundown, demanding no interference whatsoever. Regina agrees to the challenge saying that "This isn't the Wild West," while Zelena counters with, "No, dear. It's the Wicked West," and departs.
At the Vault, Regina finds a letter from Cora, affirming that Zelena is telling the truth. She is later tracked down by Robin, who, after pickpocketing it from her jacket, is allowed to read the letter. Regina learned that the letter about Rumplestilskin praising Cora's first-born was about Zelena and not her. Also, Regina tells Robin Hood that if Rumplestiltskin, the one who taught her everything she knew about magic, thinks that Zelena is more powerful than Regina (and Cora), she will have no chance of winning the fight. Meanwhile, as Mary Margaret, Emma, David, Tinker Bell, and Belle discuss how to stop Zelena, Belle thinks that she can get through to Gold without using his dagger. As a result, they head to the farmhouse, and as Belle runs down to the cellar to free Gold, Zelena appears from the background and Belle runs back upstairs, with Gold warning the others that Zelena wants them to know that if they interfere, he will kill them. In the meantime, Hook takes Henry down to the docks, looking at the sky with Hook's sextant. Henry gets suspicious about Hook after he says that he taught Neal when he was a boy, although they are the same age. Henry demands the truth. Hook then tells him Emma is trying to protect him, saying that Neal had just lost his father when he met him, and Henry has more in common with him than he realizes.
Later that night at Main Street, everyone gathers to see sisters' showdown. Zelena shows up first and means business (and uses Gold to kill anyone after five minutes), vowing to stop anyone from interfering, and proves it after Emma steps in by throwing her into her parents. Regina then finally steps up to battle, but not before slapping her older sister over the subject of their mother. Zelena responds by throwing her sister into a car; Regina counters by conjuring up a fire ball which Zelena extinguishes quickly. Zelena then throws Regina into the clock tower, and as Zelena flies up to take the one thing that she needs from Regina, the Evil Queen reveals she has known what it was all along, telling Zelena "Our mother taught me one thing. Never bring your heart to a witch fight. Something you'd know if she hadn't abandoned you." (It turns out that Regina gave her heart to Robin Hood back at the forest for safekeeping prior to the battle). A furious Zelena tells Regina that she will find her heart, and also vows to destroy her, before flying off on her broom. As everyone races to check on Regina, Regina divulges that if Zelena has David's courage and is after Regina's heart, Zelena might have something big planned. And as it turns out, Zelena is indeed planning something that will change the courses of everyone involved, telling Gold back in his cage that what she is planning isn't a curse... but a second chance.
- The episode title is a reference on "Bein' Green", a 1970 song made famous by Kermit the Frog, who was created and voiced by Jim Henson, whose Muppets properties are part of The Walt Disney Company. Ironically, the studio also produced a 2005 made-for-TV movie based around the Wizard of Oz theme featuring the Muppets, aptly titled The Muppets' Wizard of Oz.
- The Wizard's figure bore a resemblance to James Franco's character from Oz the Great and Powerful.
- The silver slippers Zelena wore in the episode are described as the same one featured in the "Wizard of Oz" book.