“Once Upon a Time” fans won’t want to miss the Season 5 installment Sunday night. The ABC series is gearing up for a special two-hour event, airing episodes 8 and 9 back-to-back.

Titled “Birth,” episode 8 puts Emma (Jennifer Morrison) in a sticky situation in Camelot. King Arthur (Liam Garrigan) now has control over Merlin (Elliot Knight), and the wizard needs Emma to hand over the Dark One’s dagger and the Promethean spark to the corrupt king. Of course, Emma’s unwilling to do so. But Arthur planned on that. He threatens to have Merlin kill Emma’s entire family if she doesn’t give in to his demands.

According to the synopsis, Emma will “face off against Arthur, Merlin and Zelena (Rebecca Mader) in an epic battle of magic.” But can Emma beat the all-powerful Merlin? The episode description reveals she’ll be forced to “make a gut-wrenching choice that no one saw coming.”

Episode 8 won’t be set solely in Camelot. Fans will also revisit the drama happening in current-day Storybrooke. The heroes are still trying to figure out what happened in Camelot after their memories were erased, but a new situation will put everything on the backburner: Zelena’s pregnancy “mysteriously accelerates.” (Hence the episode title, “Birth.”)

Although Hook previously told the Dark Swan that he wanted nothing to do with her, Zelena’s pregnancy will have him “desperate to get answers.”

The drama will continue directly in episode 9, titled “The Bear King.” In Camelot, Zelena and Arthur will continue to partner to defeat Emma and the other heroes. Their desire to beat them will bring the duo to DunBroch to “retrieve an enchanted relic.” It’s there that they’ll run into Merida (Amy Manson), who the synopsis teases is on her own journey.

When we last left Merida, she had successfully rescued her brothers and took back control of her kingdom. But now she has to “pay a debt that her father, King Fergus (Glenn Keogh), owed to the Witch when he died.” Merida’s journey will reunite “Once Upon a Time” viewers with Mulan (Jamie Chung) and Ruby (Meghan Ory), who join the “Brave” queen to “discover the identity of the knight who killed her father.”

Once Upon a Time - Ruby & Mulan Ruby (Meghan Ory) and Mulan (Jamie Chung) will return to "Once Upon a Time" in Season 5, episode 9. Photo: ABC

“Once Upon a Time” Season 5 will continue on ABC with episodes 8 and 9 Sunday, Nov. 15, at 8 p.m. and 9 p.m. EST, respectively. Watch sneak-peek videos of the two-hour event below: