'The Vampire Diaries' season 8 episode 13 spoilers, news: Kai to resurrect Elena in exchange for his freedom? Caroline and Matt struggle to save Stefan

Kai (Chris Wood) returns from hell to trade Elena's (Nina Dobrev) resurrection for something grave. Meanwhile, Caroline (Candice King) and Matt (Zach Roerig) work on keeping Stefan (Paul Wesley) sane from his dark past.

In episode 13 of "The Vampire Diaries" season 8, titled "The Lies Are Going to Catch Up With You," Kai cooks up a deal to bring back Elena in exchange for his freedom from hell.

As seen from the episode promo, Alaric (Matt Davis) is ready to make a death stab at Kai, but he blurts out "What if I brought back Elena?" which catches Damon's attention. But it appears that Damon is making Elena's return as an insurance policy as he orders Kai to bring her back immediately before working on his freedom.

Meanwhile, Caroline and Matt work together to Save Stefan from being swallowed by his dark past. The synopsis posted on The Futon Critic reads as follows: "Stefan is held captive by a surprising acquaintance and is forced to confront a dark secret from his past. Meanwhile, Caroline and Matt try to keep Stefan's violent history from destroying him. Cade (Wolé Parks) focuses his attention on Bonnie (Kat Graham) and digs deep into her mind."

It seems that the gang has their hands full. Even Bonnie has to deal with problems brought by the devil.

Dobrev has long confirmed her return for "The Vampire Diaries" season 8 finale, and she has posted several photos and videos on her Instagram account, exhibiting her return to the CW series.

The actress shared on her Instagram a dedication to "The Vampire Diaries" family on the day that they shot her last scene with the series.

Dobrev said in her post, "Coming back for the series finale has been a whirlwind of emotion, nostalgia, love, tears of joy and bittersweet endings." She also said that it was the beautiful closure that all of them needed and that she could not have been happier to have one last hurray with her "The Vampire Diaries" family.

"The Vampire Diaries" season 8 airs every Friday night at 8 p.m. ET on The CW.