The world has been saved, but it looks like it will need saving once more. Castiel (Misha Collins), feeling responsible for freeing Lucifer (Rick Springfield) from his cage, is on a mission to get him back to where he belongs. Meanwhile, Sam (Jared Padalecki) and Dean (Jensen Ackles) will meet a new character named Alicia (Kara Royster). Her interesting childhood might just add color to Sam and Dean's story.

In the "Supernatural" season 12 extended promo, a determined Castiel plans to take on Lucifer himself. Back in season 11, Castiel offered himself as a vessel to Lucifer and brought him out of his cage to help fight the darkness, Amara (Emily Swallow). In the end, Lucifer was banished from Castiel's body by Amara and now he is on the loose.

Now, in season 12 of "Supernatural," Lucifer plans to destroy all humanity and get rid of all the demons, Game N Guide reports. Castiel is determined to take Lucifer on himself to save the world from destruction once again.

With his personal mission to capture Lucifer, season 12 will be putting Castiel in the spotlight. TVLine reports that Executive Producer and writer Andrew Dabb said that the aim for season 12 is for the viewers to personal with Castiel. "To tell some stories that were a little bit more personal with Castiel, both in terms of his relationship with Sam and Dean and digging into his past a bit," Dabb said.

Not only will it focus on how Castiel connects with the Winchester brothers, season 12 will also show how he connects with Mary Winchester (Samantha Smith). Dabb explains, "He and Mary have a connection. It's not a romantic one, but they have a lot in common. They're both strangers in a strange land, in a way."

Amidst all that's happening in "Supernatural" season 12, Sam and Dean will cross paths with a new character — Alicia — who will be portrayed by "Pretty Little Liars" star Royster. According to Variety, Alicia is a fellow hunter who — along with her brother Max — was raised by a witch. The Winchesters will meet the two in episode six of season 12.

"Supernatural" season 12 premieres on Thursday, Oct. 13, at 9 p.m. EDT on The CW.