This coming Sunday, "Once Upon A Time" fans will be taken to Arendelle, the home of Elsa and Anna in "Frozen." Many people have been waiting for Season 4 of the fantasy TV series, simply because they want to see Elsa and Anna in it. And of course, it will be interesting to see how these "Frozen" characters will end up in Storybrooke or how their stories will intertwine with one another.

ABC released a 7-minute footage of the first episode to tease everyone. The video is available on ABC's website. Someone uploaded it on YouTube but it was taken down right away.

The footage reveals tons of things. The first is the shipwreck that killed Elsa and Anna's parents. In the ship, their mother goes to the cabin and writes a letter. Their father asks what she is doing and she says, "I have to finish this. They have to know. We might not make it home... but this could. Anna and Elsa must know the truth. It's the only thing that could save them."

They put the letter inside a bottle and the waves swallow the ship.

Meanwhile, in Arendelle, the story picks up right after the "Frozen" movie ends. Anna is engaged to Kristoff and Elsa will give Anna a surprise on her wedding. And there's a scene where Anna and Elsa visit their parent's graves and talk about how their parents would be very proud of them.

Later, Elsa ends up in a barn – she is now in Storybrooke. She is confused as to where she is. She wanders around and sees the town in ice. At the end of the footage, it can be seen that Grumpy and Sleepy's car almost runs over Elsa but she freezes it, reported Hypable.

After a peek into Elsa and Anna's story, Regina is seen leaving Granny's Diner. She doesn't like it that Robin and Marian reunited. She tells Emma, "Once again I felt the brunt of heroism. Always the villain, even when I'm not."

And then Robin exits the diner with Marian. Robin introduces Marian to Regina, and Marian picks up that Regina and Robin are together. Marian is upset knowing it. Then Mary Margaret and David, with Baby Neal, joins the scene. Marian wonders why everybody is friends with Regina. Later, Regina leaves the awkward scene and everyone worries if she will become evil again.

"Once Upon A Time" Season 4 returns this Sunday on ABC. The first episode is titled "A Tale of Two Sisters." If you miss the premiere episode, be sure to watch it online via live stream on ABC.