‘Once Upon A Time’ Season 5 Spoilers: ‘Swan Song’ makes fans nervous, promo videos hint at sad ending

Actress Jennifer Morrison and actor Robert Carlyle who plays both Rumplestiltskin and Mr. Gold, on the new series "Once Upon A Time" speak during a panel session at the ABC Summer TCA Press Tour in Beverly Hills , California August 7, 2011. Reuters/Fred Prouser

“Once Upon A Time” Season 5, Episode 11 (“Swan Song”) airs this Sunday, Dec. 6, on ABC. In this fall finale episode, Emma Swan (Jennifer Morrison) takes on Captain Hook (Colin O’Donoghue). The ‘Dark Swan versus Dark Hook’ development is making fans anxious. Watch the promo videos while waiting for the primetime broadcast.

Spoiler alert: This update contains major “Once Upon A Time” Season 5 spoilers. Read on at your own risk if you have yet to catch up on the latest twists in this modern fairy tale drama.

OUAT co-creator Adam Horowitz teased “Swan Song” on Twitter two months ago. The title spoiler alone made some fans worry. There are speculations that someone would die, or Emma would die as the Dark One. The first theory is tragic, while the other is optimistic. Here is a mini poll by some OUAT fans on Google+ about who might die in the fall finale episode.

Scroll down to check out Horowitz’ tweet and some of the responses he has drawn from fans of the show. The ABC promo videos show two timelines. In one video, the evil queen Regina (Lana Parilla) prepares Hook for a test to find out his weakness in the enchanted forest. Incidentally, viewers will see a young Killian (Oliver Bell) in this special episode.

In another video, Snow White (Ginnifer Goodwin) reminds Emma that she is waging an all-out war against someone she loved. Both clips seem to hint at a sad ending; both scenes are included in “Once Upon A Time” Season 5, Episode 11.

In the ABC synopsis, Mr Gold (Robert Carlyle), who is in possession of the Excalibur as of OUAT 5x10, seems to have given up. He tells the rest of the lead characters to “spend their last fleeting moments enjoying the company of their loved ones.” Emma Swan, however, is determined to win against Dark Hook, Nimue (Caroline Ford) and all the other Dark Ones.

In another teaser, Horowitz tweeted a tiny portion of the OUAT 5x11 script. The snippet contains an exchange between present-day Regina and Emma. It looks like they will partner up once again on a mission to defeat Dark Hook and all the Dark Ones who have made their way into Storybrooke.

“Once Upon A Time” Season 5, Episode 11 features the following guest stars: Lee Arenberg as Leroy/Grumpy, Adam Croasdell as Brennan, Eric Keenleyside as Maurice, Scott Hylands as Captain, David-Paul Grove as Doc, Gabe Khouth as Sneezy, Faustino Di Bauda as Sleepy, Michael Coleman as Happy, Mig Macario as Bashful, Sebastian West as Boy and Andre Tricoteux as Massive Brawler.

"Swan Song" was written by Horowitz together with his co-creator and showrunner Edward Kitsis. Gwyneth Horder-Payton directed the fall finale episode.

‘Once Upon A Time’ show boss Adam Horowitz tweets ‘Swan Song’

Here's the #OnceUponATime #titlespoiler for our mid-season finale -- hope to see ya tomorrow for a new ep! pic.twitter.com/BpVDVNTJrI
— Adam Horowitz (@AdamHorowitzLA) October 17, 2015