This Sunday, Once Upon A Time appears on television with its newest episode with Labour of Love as its title. The trailer for the episode is already out.

Once Upon A Time, created by Adam Horowitz, is a series that takes place in a fictional seaside town called Storybrooke, Maine.

Residents of this town are characters from various fictional tales, who have transported to this real world town and have been deprived of their real memories by an authoritative curse. A young woman with a troubled past is attracted to this town, says IMDB.

Here are things that will happen on Sunday’s episode of Once Upon A Time.

The Dog

The three-headed dog, which lives in Hades’ home, returns to the TV adaptation. Cerberus, also know as the hound of Hades, is a monstrous dog who is traditionally multi-headed.

Cerberus’ job is to guard the gates of the underworld and to stop the dead from leaving.

The New Hero

It was announced that this season will be featuring Disney’s Hercules. This was quite joyous for the fans, who are now able to see how the series would portray the titular hero.

The episode begins within the Underbrooke cemetery in the Underworld. Snow White (Ginnifer Goodwin) and Prince Charming (Josh Dallas) are standing over a grave.

Hercules (Jonathan Whitesell) with dark brown hair but without big muscles, lies there. Snow White tells Charming that she is acquainted to Hercules. The two were childhood friends.

“Hercules! He can help us,” says Snow White. “We save him and he can save us.”

The Hero’s Wife

Megara (Kacey Rohl) is also another character appearing on Sunday’s episode. It looks like Megara is still enslaved by Hades (Greg Germann).

Fortunately for Megara, Hook fights off “the six piercing eyes from the shadows” and thus lands himself as a hero, says Zap2it.

However, it is still uncertain if Megara is entirely trustworthy. In mythology, she was the daughter of the king of Thebes. Hercules, after saving Thebes, married Megara and they had children together, according to HISTORY.com.

According to the Disney cartoon, Megara was Hades’ tool for seducing men. Coincidentally, the sneak into the trailer revealed that she still knows the trick when it comes to Hook.

It is somewhat certain that both Hercules and Meg have “unfinished” business in the Underworld.