"Once Upon a Time" returned from a lengthy hiatus with an amnesiac Emma and a wicked new villain.

"New York City Serenade" opens with Aurora (Sarah Bolger) and Phillip (Julian Morris) in the Enchanted Forest, and a purple cloud appears overhead. The cloud brings Snow (Ginnifer Goodwin), Charming (Josh Dallas) and the other Storybrooke denizens back to the Enchanted Forest.

The show then flashes a year ahead to fancy restaurant in New York City. Emma (Jennifer Morrison) is on a date with a man named Walsh (Christopher Gorham). When Walsh steps away from the table, Hook (Colin O'Donoghue) appears to tell her that her family is in peril.

Emma has no memory of her fairytale family, and thinks Hook is a stalker. Hook gives her a piece of paper with an address written on it, and tells her that she'll find out who her parents are if she goes to the address.

Walsh then comes back to the table and pops the question, which makes Emma nervous and a bit confused.

The show flashes back to a year ago in the Enchanted Forest. Aurora tells Phillip that they have to tell "you know who" that Snow has returned, but Phillip tells her that Snow and the rest will be hurt if they tell. But if they don't, "you know who" will come after Aurora's child.

Back in NYC, Emma goes to the address Hook gave her to find that it's Neal's (Michael Raymond-James) apartment. She sees that Neal has a camera with Henry's name stitched to the strap, and doesn't understand why. She takes Henry's camera back and goes to find Hook.

She finds Hook in the park and demands some answers. He tells her to drink a memory potion to help her remember everything, including who her parents are. This really makes her think Hook is crazy, so Emma has him arrested for harassment.

Back in the Enchanted Forest, a flying monkey appears out of nowhere and attacks Regina (Lana Parrilla). Regina throws a fireball at the creature, but misses. Robin Hood (Sean Maguire) and Little John get there in the nick of time to save her, and they say have never seen such a creature in the forest before.

Once they get to the castle, Regina finds that her castle is surrounded by a protection spell.

In New York, Emma develops the photos from Neal's camera and sees that there are photos of trips to Storybrooke, but she has no memory of ever being there.

Realizing that Hook may be telling the truth, she bails him out of jail and agrees to drink the potion. She instantly remembers everything, and sees that she's been living in blissful ignorance. Yet, there is only one dose of memory potion, which means there is not enough for Henry.

Emma then tells Walsh that she can't marry him because she still has issues to deal with from her past. Walsh says to her: "You had to drink the potion. You couldn't leave well enough alone."

Emma is shocked to hear that he knows about the potion. Then, Walsh transforms into a flying monkey in front of her. He goes to attack her, but she escapes.

She then tells Henry that she is taking a business trip to Maine with Hook, and that Henry should come along. She doesn't tell him that she is actually going to see her parents.

Once they're in Storybrooke, David opens the door, and remembers her, but says he doesn't remember the last year. Yet, he says he knows a lot of time has passed because Mary Margaret is pregnant.

The episode ends with another flashback to the Enchanted Forest, in which the flying monkey brings Regina's blood to the Wicked Witch of the West (Rebecca Mader), which will be used for to exact revenge.

On the next episode, "Witch Hunt," Emma believes that someone in Storybrooke is responsible for the curse that made everyone lose their memories. She teams up with Regina to find out who used the curse.

The next episode will also show the Wicked Witch's alter ego, Zelena, who is a midwife.

Meanwhile, in the Enchanted Forest, Regina and Robin Hood will try to regain her castle, which has been taken over by the Wicked Witch.

Check out some photos from the upcoming episode here. 

Also, on a future episode, Hook may try to rekindle his flame with Emma. Colin O'Donoghue spoke to TVLine about the possibility of the two characters getting together.

"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!" he teased.

Watch the promo below for "Witch Hunt," which airs Sunday at 8 p.m. EST on ABC.

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