Our tale begins in Fairy Tale Land many years ago, as a young woman approaches her simple home to find her drunken father napping on his sacks of flour. She chides him for his laziness and takes the flour to market herself. There, a smug and mean-spirited young Princess trips her, sending her sprawling on the ground and costing her several bags of flour. To make matters worse, the King himself shames The miller's daughter, who we learn is Cora, forcing her to apologize to Princess Eva-the young lady who will one day become Queen and Snow White's mother. Cora reluctantly does so, but seethes with rage at the injustice done to her.
In Storybrooke, The Jolly Roger arrives with the injured Mr. Gold aboard. Cora and Regina have his dagger, but they dare not use it now out of concern that forcing him to kill Emma, Mary Margaret, David and anyone else that stood in their way would hasten his death and the powers of The Dark One would be lost forever. Instead, Cora decides that she has no choice but to kill Rumple with his own dagger first and become the new Dark One herself. Regina seems to begin suspecting that getting Henry back isn't really what Cora's after.
Meanwhile, the heroes of Storybrooke hide Mr. Gold in his pawn shop and use whatever magical tricks he has up his sleeves to barricade themselves in. Emma uses some invisible chalk and even gets a crash course from Gold on casting a magical protection spell. As everyone heads to the front of the shop, Gold asks Mary Margaret for a warmer blanket, pointing her to an old wardrobe. Inside, she doesn't find any blankets, but she does find a familiar magic candle-the one she was given as a young girl in episode 215, “The Queen is Dead”! The candle has the power to save a life in exchange for taking another. In this case, she could light the candle and whisper Cora's name over her heart. Then she'd have to get Cora's heart back into her body to transfer Mr. Gold's mortal wound to Cora. Since she refused to use the candle to save her own mother, Mary Margaret's not really interested in using it to save Mr. Gold. Her plan is to get Cora's heart and use it to take control of her. With that, she could force Cora to do the right thing, but, as Gold points out, then she'd be letting Henry's grandfather die.
In Fairy Tale Land, Cora steals a nice dress and crashes a masquerade ball being thrown as a means of introducing Prince Henry to wealthy young women whom he could marry to increase the kingdom's fortunes. The ruse doesn't last long before the King catches on to Cora. He again insults her and this time she claims she can spin straw into gold. He challenges her to prove it. She is to spend a night loked in a tower full of straw with a spinning wheel. By morning she will either have proven her outrageous claim or be executed. Needless to say, Cora is in way over her head when suddenly Rumplestiltskin appears. He has seen the future thanks to the powers he gained in episode 214, “Manhattan” and he knows he'll need Regina to get his Dark Curse cast. He offers Cora a deal-he'll spin all of the straw into gold in exchange for her first-born child. Cora accepts the deal, but only on the condition that he teach her how to spin straw into gold herself. He does, and the two grow very close in the process. By morning, she is spinning straw into gold as promised and wins the hand of Prince Henry.
The day of Cora and Prince Henry's wedding approaches, but she has clearly been seeing Rumplestiltskin on the side. As they meet for what may be the final time before she is married, they decide that perhaps they should run away together. Rumplestiltskin is so taken with Cora, he even amends their deal so that Cora promises to give him HIS child. Cora only has one more thing to do. She wants revenge on the King for humiliating her. She wants to rip out his heart and show it to him before he dies. Coincidentally, Rumplestiltskin is great at that. He teaches her everything she needs to know about ripping out hearts and they plan to meet outside the castle walls that night after she's done the deed.
Cora visits the King in his chambers, where the cold and pragmatic ruler lays out the facts plainly. He knows she's been seeing Rumplestiltskin and he knows she has to decide whether to run away with him for the sake of love or to stay and rule a Princess by marrying his son-who he himself doesn't even seem too fond of. Presented so clearly as a choice between love and power, Cora makes her decision. That night, she meets Rumplestiltskin and dispassionately tells him that she is going to stay and marry Prince Henry, rather than go with him. He asks what happened and whose heart she now carries in a box. The heart is her own, which she removed herself, to keep herself from choosing love over power. Rumple is hurt and outraged and reminds Cora of their deal. But Cora reminds him that he amended the deal and she would never have a child with him.
In Storybrooke, Regina and Cora burst through the magical barrier protecting Mr. Gold's shop. After a quick tussle, Mary Margaret slips out of a side door to find Cora's heart. David is magically thrown out of the shop and, while Neal and Emma hold their own as best they can against two sorceresses, they wind up backing into the store room with the dying Mr. Gold and sealing it up with more magic. As Cora prepares to break through, she realizes something's amiss with her heart and sends Regina off to protect it.
As Cora hammers the magical barrier, Mr. Gold begins to realize the end is near. He calls Belle, who's still in the hospital with no memory of her true self, and tells her he knows who she is. He finds words of such love and tenderness for her, it's almost impossible to believe that they're coming from The Dark One. Neal and Emma overhear everything and Neal is shocked to hear his father's dying words to a woman he loves. While it's not a complete reconciliation, father and son come together in what may be the few moments they have left together.
Meanwhile, in Regina's hidden chambers beneath her family mausoleum, Mary Margaret finds Cora's heart. She ponders for a moment, but then does the unthinkable, lighting the candle and whispering Cora's name over her heart. After the deed is done, Regina finds her there, holding the box with her mother's heart. But Mary Margaret tricks Regina, telling her that putting her mother's heart back in her chest will be the only way for Cora to truly love Regina and for them to really start a family that Henry may one day be able to be a part of.
Back in the store room, Cora finally bursts through. She quickly banishes Emma and Neal to the woods outside of town and stands ready to finish off Mr. Gold. She sits with him for a moment, admitting that she did truly love him once, and that was why she had to take her own heart out. Just as Cora's about to plunge the dagger into Gold, she shudders as her heart is jammed back into her body. She turns to see Regina there and finally looks on her with love in her eyes.
Overwhelmed with love for her daughter, Cora smiles and laughs uncontrollably. Regina seems truly happy for just a moment until suddenly Cora shudders again and collapses. Mr. Gold looks to his chest where his wound is now gone and realizes what's happened. As Regina cradles her dying mother in her arms, Cora realizes that the love of her daughter would have been enough-that all of the power she'd sought to possess was meaningless in comparison. But just as that truly dawns on her, she dies.
Too late, Mary Margaret rushes in screaming for Regina not to put Cora's heart back. Regina realizes what's happened and looks up and her old enemy with fury in her eyes. The Evil Queen wants revenge against Snow White now more than ever!