As Storybrooke descends into chaos as the Snow Queen's spell takes hold, Emma and Elsa try to trick Regina into destroying the ribbons so that they can attack the Queen. In the past, Ingrid adopts Emma and attempts to show the girl that she's a powerful sorceress.

Emma is still reeling after learning the truth of her parents’ history with Maleficent, but she must focus on finding the Author, who is running loose in Storybrooke, before Gold does. When Gold’s quest for his happy ending grows more urgent, he blackmails Regina into helping him. In a Fairy Tale Land flashback, Robin Hood learns what it means to be an honorable thief when he accepts a proposition by Rumpelstiltskin to travel to Oz to steal a valuable magic elixir from the Wicked Witch.

In a Camelot flashback, a chance encounter with Merlin, David, Hook and Belle gives Merida new hope in her quest to save her brothers from the usurping clans of DunBroch. Unwilling to leave anything up to fate, Merida brings Belle along on a dangerous journey that culminates with an invaluable lesson in bravery. In Storybrooke, Regina, Mary Margaret and David discover the spell that would allow one of Merlin’s chosen to communicate with him, but when Arthur fails to reach the missing sorcerer the heroes grow suspicious. Meanwhile, Emma commands Merida to kill Belle in hopes of forcing Mr. Gold’s heroic transformation. With Merida unable to disobey Emma’s orders.

In a Camelot flashback, Hook becomes a Dark One and his lust for revenge against Rumplestiltskin is reignited. When Emma and Hook disagree about their best course of action, the final pieces of the puzzle are revealed as events in Camelot catch up to the present and we witness a charged confrontation between the forces of light and dark that sends our heroes on a collision course with destiny. Meanwhile, in Storybrooke, Hook’s centuries old lust for revenge against Gold puts both of their fates in jeopardy while Emma’s love faces the ultimate test as she tries to convince Hook to turn away from the darkness before she, Mary Margaret, David and Regina embark on a new mission as an unsuspected evil is released.

Emma, Snow, David, Regina, Robin, Henry and Hook continue to search for a way to free everyone from the Underworld. At the mercy of Hades, Gold creates a portal to Storybrooke, which transports Belle, Zelena and Baby Hood to the Underworld. While Zelena and Regina get into a sibling squabble, Belle is reunited with Rumple only to learn some tremendously shocking news that will change her life forever. Meanwhile, Snow and David hopelessly attempt to send a message from the Underworld to their son, Neal. In flashbacks, Hades learns about Zelena’s very special spell and pays her a visit in Oz with the intention of striking an alliance, but finds himself with more than just a partner in crime.