The big day is finally here! After being off the air for a couple months, “Once Upon a Time” finally returns to ABC at 8 p.m. EDT with its Season 5 premiere.

Fans of the fairytale drama may be ecstatic to reunite with their favorite characters, but where did the series last leave off? We’ve got a recap of the Season 4 finale.

Viewers finally learned the history behind Isaac, the Author (Patrick Fischler) via a flashback to 1966. He was a normal human living in our world as a TV salesman and aspiring writer. Unfortunately Isaac wasn’t a great TV salesman, but the Sorcerer’s Apprentice did see potential in his writing. With nothing to lose in his world, he accepted the position as Author and traveled into the other worlds.

Meanwhile in present day, the good folks of Storybrooke have to deal with the Author’s power trip. Despite their best efforts to return him to the pages of the storybook, the Author writes the fairytale characters into a whole new world – “Heroes and Villains.” However, one person does not get transported to this new world – Henry (Jared S. Gilmore).

In this alternate universe, Isaac is a best selling author of “Heroes and Villains,” a book that flips the good and evil characters. Henry wants to get his friends and family back and seeks out Isaac to change the ending. However, Isaac is not willing to help Henry. He claims that he no longer has the power of the pen because he chose to write his own happy ending. Henry’s not one to give up though. He uses the key from the Sorcerer’s Apprentice to transport him and the Author into the pages of “Heroes and Villains.”

The only way for Henry to save everyone is to change the story. However, the odds are stacked against him. For starters, they are transported to the final chapter of the book, meaning that time runs out when the bell tower strikes. On top of that, no one believes Henry. And the Author is also doing everything in his power to make sure that Henry doesn’t change a single thing until the bell rings.

Henry manages to narrowly escape an ogre attack and finds Regina (Lana Parrilla) in the woods. He tries to tell her the whole story, explaining that she has the power to change everything if she kisses her one true love, Robin Hood (Sean Maguire). But Regina doesn’t believe him. She explains that Robin Hood is actually her competition, and that nothing would drive her to kiss him.

While Henry tries to hatch another plan, the Author gets captured by Snow White’s knights. In this universe Snow White (Ginnifer Goodwin) is the “evil queen” and is bent on destroying Regina. When the Author tells her that a boy named Henry is helping Regina she makes it her mission to find him and kill Regina.

With the Author’s help, Snow White is able to capture Regina. But Robin Hood rescues her before Snow White can crush her heart. Regina feels a connection with Robin Hood despite her previous ill feelings towards him. But there is a complication – he’s set to marry Zelena (Rebecca Mader) by the end of the day.

Once Upon a Time 4 Zelena (Rebecca Mader) and Robin Hood (Sean Maguire) had to be stopped from getting married in the "Once Upon a Time" Season 4 finale. Photo: ABC

Regina is discouraged by this new revelation, forcing Henry to hit plan B – find Emma (Jennifer Morrison). Henry goes to the Jolly Roger get Hook (Colin O’Donoghue) on board with his plan. But Hook is not the brave pirate he knows in Storybrooke. Instead he’s a deckhand for Captain Blackbeard. Knocking out Blackbeard, Henry convinces Hook to help him steal the Jolly Roger and find Emma in a locked tower on an island.

The two succeed, and fortunately Emma still has her memories of her past life. However, the group is met at the docks by Snow White and Charming (Josh Dallas). Hook is stabbed by Charming and left for dead when he tries to help Emma and Henry escape.

Desperate to bring Hook back to life in Storybrooke, Emma and Henry finally convince Regina to help them. They race to the church to stop Robin Hood and Zelena from marrying, however Rumpelstiltskin (Robert Carlyle) is waiting there for them. Emma encourages Regina to run ahead while she fights Rumpel, but she’s no match for the Dark One. She gets knocked out, leaving Henry to face him. But just like Emma, Henry does not have the power to defeat him. Just as Rumpel is about to kill him, Regina throws herself in front of his sword.

Robin Hood races outside to help Regina, causing Zelena to turn green with jealousy. However, the bells begin to ring, signifying that Emma and Henry failed at changing the ending … or did they? Henry picks up the Author’s magic pen. The instrument begins to glow, revealing that Henry now has the power of the Author.

With Regina’s blood he writes that her sacrifice undid the Author’s spell. It works, sending everyone back to Storybrooke.

Once Upon a Time 2 Henry (Jared S. Gilmore) saved Regina (Lana Parrilla) in the Season 4 finale of "Once Upon a Time." Photo: ABC

Back in Storybrooke, the Sorcerer’s Apprentice talks to Henry about his new role as the Author. But Henry’s not interested. He breaks the pen in half, explaining that no one should have that much power. But that doesn’t change that Henry was still chosen. The Sorcerer’s Apprentice says that they finally found the right person for the job.

While it seemed like everyone was getting their happy ending, Rumpel was dying. His death would release the darkness into the world – something that could destroy everything and everyone. With the help of the Sorcerer’s Apprentice, the group of heroes tries to place all of the Darkness into the Sorcerer’s hat. However, the plan backfires and releases the darkness into Storybrooke.

It seeks out Regina, but Emma’s not willing to let her friend turn dark. Knowing that it needs a human soul, Emma sacrifices herself to the darkness … but not before asking her friends to find a way to save her and telling Hook “I love you.”

The Season 4 finale ends with Emma getting swallowed up by the darkness and the Dark One’s dagger dropping to the ground … etched with her name.

Once Upon a Time Emma (Jennifer Morrison) became the new "Dark One" during the Season 4 finale of "Once Upon a Time." Photo: ABC

"Once Upon a Time" Season 5 will premiere on ABC on Sunday, Sept. 27 at 8 p.m. EDT. The Storybrooke characters will be working to find a way to rescue Emma from the darkness in episode 1.