When 'Once Upon A Time' returns for Season 5 on ABC on Sept. 27, fans will see Emma Swan transforming into the Dark Swan.

According to IB Times, in 'Once Upon A Time' Season 4 finale, viewers saw that although Gold eventually getting free of the dagger's clutch, darkness tries to take Regina. Subsequently, Emma sacrifices herself and is quickly taken away by the dark powers, only leaving the dagger behind with her name engraved on it, thus making her the Dark Swan.

Recently a report in TVGuide shared some spoiler details about the 'Once Upon A Time' Season 5 premiere plot. The spoiler reads, "Emma's friends and family, led by Regina, will try to find a way to save her before she becomes the full-on Dark Swan. But this means tracking down the sorcerer Merlin, which brings them to Camelot and the Knights of the Round Table. Brave archery lass Merida (Amy Manson) will join the show as well."

Meanwhile, 'Once Upon A Time' co-creator Edward Kitsis revealed, "This is a mash-up show," adding, "This is the show where the Wicked Witch is sisters with the Evil Queen, and they also know Cruella De Vil. So what a bummer if we had King Arthur and him never got to meet Merida."

Morover, King Arthur and Charming will be seen in a very close relationship, while Robin will try to work out a way to take care of accidentally impregnating his girlfriend Regina's wicked half-sister.

Jennifer Morrison and Colin O'Donoghue who portray Emma Swan and Hook in the series respectively, shared some details about Dark Swan and the relationship between their characters in the upcoming season of the series.

According to Morrison, "Emotionally, it's interesting because there's something really fun and free about Emma in the darkness. She's just free of the gravity of what other people think the gravity of worrying about saving people."

He went on to explain, "There's lightness in a sense in the darkness because she doesn't have to do the right thing. She doesn't have to try to be the stronger, better person all the time." Morrison also teased, "She [Emma] is going to be fighting against the darkness."

On the other hand, Colin O'Donoghue teased that for Hook saying that there is "nothing is more important to him in this moment than Emma," and added, "He has spent so long fighting the darkness and hating the Dark One, so it's very complicated for him. He's trying to figure out a way to bring her back."