It is still a month away before the fifth season of "Once Upon a Time" returns on ABC, but actor Josh Dallas already started to reveal what fans should look forward to in the second half of the season.

The actor told Entertainment Weekly that some of the souls that are trapped in the Underworld are not supposed to be there in the first place.

"It's a place that, once they get there, they're going to discover that possibly [that] some of these people can be saved and brought out of there, because maybe they're misplaced in this world," Dallas revealed.

The actor also mentioned that his character Prince Charming and the other characters from Storybrooke will see other people who fans will never expect to be there or have not seen for a long time, including one of Charming's family members.

"There is definitely a particular person down there for David that he's going to come across, and Mary Margaret (Ginnifer Goodwin) will come across that person too," Dallas teased.

The return of "Once Upon a Time" season 5, which also happens to be the 100^th episode of the series, will also introduce a new big bad Hades, portrayed by actor Greg Germann.

"Hades is such a fun, endlessly creative challenge. Anything goes," the actor said about the character. "The creators bring him to life on the page with the same out-of-the-box unpredictability that they bring to the rest of the show. They strike the perfect balance between keeping things grounded and letting things fly — sometimes literally."

Series executive producer Edward Kitsis also described Hades as a very dangerous creature who is also fun to watch. But Storybrooke residents will not have any fun whenever he is around them.

Kitsis also revealed that the chances for survival for Storybrooke characters in the Underworld is very slim, especially since their past enemies are there.

"Once Upon a Time" season 5 returns on March 6 on ABC.