Plot summary
All of the residents of Storybrooke try to prevent Zelena from getting Snow's newborn baby, which is very close to arriving, because Zelena plans to use the baby to travel back in time and rewrite her destiny, while obliterating Regina and Snow White's family from existence. In the past of the land of Oz, Glinda tries to convince Zelena to fight the evil within her, and to join her and her sisters, the other good witches who protect Oz. Additionally, a young girl from Kansas is introduced who threatens to be Zelena's undoing, and ultimately factors into Zelena's final decision.
Credits
Adapted from Wikipedia contributors, Once Upon a Time season 3. HTML formatting and reference markers removed.