Immediately after becoming the Dark One, Emma disappears and the heroes must band together to save her, but first they have to find her, which will require the help of an unlikely ally. Meanwhile, in the Enchanted Forest, Emma struggles to resist her dark urges as she searches for Merlin in the hope that he can stop her transformation. Along the way to Camelot, she gets help from the plucky and brave warrior princess Merida, as well as King Arthur and his Knights of the Round Table.

With Snow still asleep in Storybrooke, David and Hook race to stop Gideon before he can confront Emma. Meanwhile, Regina struggles with the realization that everyone, even Robin, is better off in the alternate world where the Evil Queen was defeated. And when Emma inspires a familiar face to help her and Regina return home, she discovers the power to change her fate.

Trapped in Neverland, Hook aligns himself with Tiger Lily, hoping to find a way back to Emma. In Storybrooke, Regina works to break the sleeping curse that David and Snow are under, and Gold denies The Black Fairy, which brings the two of them to a fearsome impasse.

In flashback, Snow and Charming make a special wish that Emma will be protected. The result of their wish has the whole kingdom bursting into song which infuriates the Evil Queen. Meanwhile in Storybrooke, the Black Fairy announces her plans to unleash another curse on the town while Emma and Hook prepare for their wedding.