The Wicked Witch of the West, said to be one of the most evil witches to have existed, has descended on Storybrooke just as its residents are grappling with a curse that has wiped away their memories.
In the upcoming episode, titled "Witch Hunt," the residents of Storybrooke do not remember how they came back to the town, and they have no recollection of the year they spent in Fairy Tale Land. The residents also notice that several members who have tried to leave the place have disappeared.
Promo of Sunday's episode shows that these disappeared members are being turned into flying monkeys. The Wicked Witch's alter ego is Zelena, a midwife.
Emma, who returns to Storybrooke with Henry is sure that someone in town is responsible for putting the memory curse. When Emma calls a meeting to calm the residents and find out a way to break the memory curse, town folks are quick enough to blame it on Regina, the Evil Queen.
But Emma believes Regina hasn't gone back to her evil ways and they team up to get to the root of the problem.
Meanwhile, fans of "Once Upon a Time" can expect to see romance brewing between their favorite characters in the upcoming episodes.
A bit of love in Regina's life is believed to have prompted her to shun her evil ways and help the people of Storybrooke.
A previous episode showed Regina stating that her true love is the man with the lion tattoo, and it is later revealed that Robin Hood is the person she is talking about. Spoilers of the upcoming episodes also note that a few sparks might fly between Regina and Robin Hood.
Love is also on the cards for Emma and Hook.
Addressing the possibility of the two characters coming together, Colin O'Donoghue, who plays the pirate in the series, told TVLine: "Hook has very much put his feelings on the table there for Emma, to sort of take and do with however she wants. So who knows? But I'm sure he probably would really like to have another kiss!"