Poor Storybrooke is facing doom and gloom in the Season 5 midseason finale of "Once Upon a Time." Dark Hook (Colin O'Donoghue) has successfully raised the previous Dark Ones from the underworld, and it's up to the heroes to stop them from snuffing out the light. The fairytale characters have never faced a situation so dark -- and some have already given up hope.

Episode 11 begins with a flashback to a young Hook. In the flashback, the boy is scared of a storm. But his father eases his worry by telling him to “look inside” to find his bravery. It’s a sweet moment between father and son. But it doesn’t last long. When Hook wakes later on, he discovers that his father is gone. The ship’s captain comes in to tell Hook and his brother that their father was a thief and fugitive from the law. What’s worse is that he traded his two sons for a boat to escape.

“Now you know what kind of man your father really is,” the captain tells Hook.

Cut back to present day and Emma (Jennifer Morrison) is working hard to stop Hook before things get out of control. Everyone’s ready to chip in and help -- even if it means that Emma has to “take care” of Hook. Mary Margaret argues that Emma loves Hook. However, Emma tells her that the man she loved died back in Camelot.

Unfortunately for Regina (Lana Parrilla) and Robin Hood (Sean Maguire), a rogue Hook isn’t the only problem on their hands. Zelena (Rebecca Mader) isn’t that fond of the custody agreement they forced on her and decides to take sole custody of her and Robin’s daughter.

“I’m going to teach her how to be wicked,” she says to a horrified Robin.

Regina has no intention of letting Zelena win, but her half-sister tells her that she won’t have a choice – because she’ll be dead soon.

What exactly is Zelena talking about? The Dark Ones arrive and mark almost every one in town. When the moon reaches its peak, those marked will get dragged to the underworld.

The Storybrooke heroes have faced almost every form of evil over the years, but according to Gold (Robert Carlyle), there is no stopping the Dark Ones. Even though Emma is unmarked and ready to go to battle, Gold tells everyone that it is a fight they cannot win. He encourages them to use their time wisely by saying goodbye to their loved ones.

Surprisingly, Mary Margaret wants to listen to Gold. She doesn’t want to be caught in a book when the Dark Ones come to take her to the underworld. Instead, she wants to be surrounded by family. Emma’s not ready to give up, so the pair hug it out and make an agreement to meet later at Granny’s to say goodbye.

But Emma has an actual plan. She meets with Regina and reminds her of the agreement they once made in Camelot – the agreement she made to stop Emma no matter what. So, what’s the game plan? Put all the darkness into Emma and use Excalibur on her.

Regina doesn’t like the plan, but she agrees to help. Together the two go to see Gold, who just got done tricking Belle (Emilie de Ravin) into leaving town to see the world. They need Gold to hand over Excalibur, and, shockingly, he does so without trying to make a deal. He gives it to Emma, telling her that the sword was always destined to be in the hands of a hero. 

With time running out, Regina and Emma split up. Emma goes to Granny’s to say goodbye to her family, while Regina decides to take care of Zelena. She uses an old wand to summon a twister to blast Zelena back to Oz. But Zelena warns Regina that she’ll see her again.

Meanwhile, Emma might not see her family again. Instead of going to say goodbye, Emma sneaks in to leave them a note on the jukebox.

“I’m sorry,” she says before walking out of Granny’s. “It’s the only way I could make up for what I’ve done.”

Hook watches Emma leave and knows what she’s up to. Unfortunately, Nimue (Caroline Ford) knows as well. She tells Hook that he knows what he must do.

Emma and Hook come face to face at her house, but things don’t go as planned. Hook tricks Emma by using dark magic to turn himself into Henry (Jared S. Gilmore). He then easily removes Excalibur from her hands, once again gaining control over the powerful weapon.

The loss of Excalibur means that Emma is back at square one. And while that’s not good for Storybrooke as a whole, it’s good for Mary Margaret, who stumbles across Emma’s note. Mary Margaret, David (Josh Dallas) and Henry are ready to stop Emma, but Nimue gets to them first. She tells them that Hook already got to Emma before she could use her powers to transport them all to the lake.

Regina, Robin Hood and Gold are already there, and it appears as if time has run out. As Hook jokes, the “S.S. Purgatory” arrives to take them all to the underworld. However, Emma runs up just in time to say goodbye. Despite being the Dark One, Emma’s got tears in her eyes. She’s upset that she put her family in this situation. But Regina has one more trick up her sleeves. She reminds Hook about a decision he made a long time ago about the man he wants to be.

Another flashback reveals more about Hook’s past. This time the flashback is set when Regina was the Evil Queen who ruled the Enchanted Forest. She wanted to hire Hook to kill her mother. In exchange she would bring Hook to a world without magic so that he could get revenge on the Crocodile. But, of course, there was a catch. Hook needed to pass a “test” first before Regina sent him after her mother.

Regina brought Hook to a bar and told him that there was a man inside he needed to kill. Hook told her that it was no problem -- until he learned that the man he needed to kill was his father.

Although many years had passed, Hook’s father was just like him -- immortal. And just like Hook, he changed. While Hook had embraced his inner evil, his dad claimed that a woman changed his life. He cried and apologized to his son, prompting Hook to make a deal with him. Hook said that although he came to kill him, he’d be willing to fake his death and allow his father to start again somewhere else.

Hook’s father was grateful, but then asked  for a favor – allow him to take his son with him. His new son was about the same age as Hook when he abandoned him, and it pained the pirate to see his father doting on another child. But what really upset Hook was that his dad named his new son Liam, the same name of Hook’s late brother.

His father argued that he was just trying to honor Liam and that the name reminded him not to make the same mistakes twice. However, Hook didn’t believe that his dad changed. He burned the passes that would allow his father a chance to start over and stabbed him in the chest.

As his father lay dying, he told Hook that “it’s never too late.”

“You can change,” he said.

Cut back to present day and it’s time for the marked ones to go to the underworld. In order to stop Emma from interfering, Nimue begins to choke her with magic. However, Hook steps in to stop Nimue.

“That’s enough,” he warns her. And when Nimue asks what he’s doing, he tells the original Dark One that he’s “being the man I want to be.”

Hook takes Excalibur and uses it to gather all of the Dark Ones' magic. Emma begs him that it should be her, but Hook argues otherwise. He tells her that her family needs her and that if anyone deserves to go to the underworld it’s him.

“Let me die a hero,” he says. “That’s the man I want you to remember.”

Despite the tears running down her face, Emma takes Excalibur. The pair exchange a kiss and say “I love you” one last time before Emma plunges it into Hook’s chest. The power turns Emma back into her old self and Excalibur disintegrates. Hook’s neck wound returns and he collapses into Emma’s arms.

Emma’s a mess as Hook’s body is carried away. But one person in Storybrooke did get their happy ending. Belle returns after discovering what really happened in town. Although Gold lied to her, she kisses him and thanks him for being “truly selfless.”

“I don’t need to see the world to know what I want anymore,” she says, promising Gold that she wants to be with him.

But Gold’s hiding something. Now back at her home, Emma begins to hear whispers again. She texts Gold to meet at his shop, and it’s there that she confronts him about the whispers.  The whispers mean the dagger is nearby and she can sense that it’s in his shop.

Gold removes the dagger from underneath the counter and exposes the blade. The names Emma Swan and Killian Jones are no longer etched on the dagger. Instead, the name Rumplestiltskin is once again engraved.

It turns out that Gold saw an opportunity and turned Excalibur into a conduit. Hook had no idea that he was moving the magic and channeling it somewhere else. Now Gold has the combined power of all Dark Ones that ever lived -- including Emma.

Needless to say, Emma is not too thrilled that Gold found a loophole and betrayed everyone. But what’s really got her upset is that Killian didn’t get to die the hero he wanted to be.

With this new knowledge on her side, Emma makes a deal with Gold. She promises to keep quiet to Belle if Gold “does something” for her. But what does she want?

Emma goes to Mary Margaret, Regina and the others to explain her plan. Gold’s going to send her to the underworld and she’s going to get Hook back. Although the rules state that you have to trade a life for a life, Emma tells her family and friends that she’s giving into “love, not darkness.” Her plan is to share a heart with Hook.

“It could work,” Regina says.

Together the group returns to the lake with Rumple, who opens up the portal to the underworld again.

“Hook, I will always find you,” Emma say before boarding the vessel.