Damon will literally begin digging for the truth about his mother, who may or may not be alive, while Caroline will unleash her dark side in Thursday's all-new episode of "The Vampire Diaries."

During the last episode, Caroline decided to flip her humanity switch off after she buried her mother and Stefan led her to believe that he does not have romantic feelings for her. In addition, Damon discovered that his mother, who he initially believed was dead, may actually be trapped in another prison world.

In the upcoming episode, which is titled "The Downward Spiral," viewers will learn more about Damon and Stefan's mom, Lily, teases Wet Paint. Meanwhile, Damon will pressure Kai to give him information about the prison worlds, even if it means that he will learn "devastating news" about his mother.

A sneak peek reveals that Damon will be in denial when Kai tells him that his mother is still alive and living in a 1903 prison world. Damon will also dig up his mother's grave to prove that she was really buried.

"You wanted to know if it was possible for her to exist in another prison world, to which I responded yes, to which you responded with denial," Kai tells Damon in the clip.

"Whatever, whoever is on that tape is not her," Damon insists to Kai in response. "I know my mother. She is not a vampire. She is not in a prison world. She died of consumption in 1858."

During an interview with TV Guide, actor Ian Somerhalder opened up about the mixed emotions his character, Damon, will experience as he searches for answers about his mother.

"The two most important women in his life, Katherine and his mother, abandoned him and didn't love him. That's a gnarly thing. So, he's going to spend some time trying to find out what really happened. It's a brutal thing for him to go through and he's going to have to figure it out," he said.

Executive producers Julie Plec and Caroline Dries also dropped spoilers about "The Downward Spiral," which will mark "TVD" star Somerhalder's directorial debut.

According to Plec, the centerpiece of the episode will be a rave party, which Somerhalder had a lot of fun shooting, probably because "he's been to a rave or two in his life," she said with a chuckle.

"We have a huge party in this episode, which was a lot of fun to shoot," Somerhalder told TV Guide.

He also teased a scene with Bonnie and Damon after Bonnies gets "fed up."

"She always gets hurt and is always the fall girl, and it's always so intense for her. She tries her hardest to help people and it always backfires on her. This experience in the prison world made her a woman, and she's no longer going to deal with this bulls-t."

Meanwhile, Stefan will feel responsible for Caroline's downward spiral after she flips off her humanity, removes her clothes from her dorm and then goes missing.

Somerhalder also teased that things may not last between Damon and Elena.

"I don't think that's absolutely going to happen, but I think they're trying. The situation is very intense and it's hard. But you definitely see [him putting in effort] and you don't always see that side of him. So, that's cool."

According to Wet Paint, the synopsis reads as follows:

"After shutting off her humanity following the death of her mother, Caroline gives her friends an unexpected ultimatum. Not knowing how to handle the new Caroline, Stefan's attempt to intervene sets off a dangerous chain of events, leaving him and Elena (Nina Dobrev) in a race against the clock. Meanwhile, after seeking answers from Kai about the prison world, Damon's world is turned upside when he learns some devastating news about his mother Lily. Elsewhere, Enzo (Michael Malarkey) finds himself becoming increasingly intrigued by Sarah Salvatore (Tristin Mays), and Bonnie begins to struggle with the effects of being back in the real world."

Season 6, Episode 15 of "The Vampire Diaries," titled "The Downward Spiral," will air Thursday, March 12 at 8 p.m. ET on The CW.

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