'The Vampire Diaries' Season 6 SPOILERS: Bonnie Tries to Commit Suicide

After two weeks of no news from Kai's hell, where Bonnie (Kat Graham) is trapped, "The Vampire Diaries" fans get an unsettling message from the witch in the next episode of the vampire drama.

Season 6 episode 13 is titled "The Day I Tried to Live," which will see Elena (Nina Dobrev) and Damon (Ian Somerhalder) convincing Jeremy to celebrate Bonnie's birthday. But they get some disturbing news from the birthday girl when they try to put together the ascendant and get in touch with Bonnie.

"Please tell everyone that I'm sorry." Bonnie declares in a video message to Elena and Damon, and this prompts the others to embark on a rescue Bonnie mission. Chances are high that the gang will succeed in saving Bonnie, as executive producer Caroline Dries previously said that the alone-time in Kai's (Chris Wood) hell is going to toughen up Bonnie.

"Bonnie, who's one of the strongest women on our show, will prove that she's not going to be down in the dumps," Dries explained to TVLine in December. "She tries to make the best of things, and it will help shape her into the character she's going to become starting in the 2015 episodes, where she's going to harden a little bit."

 But the upcoming episode is going to be a low point for Bonnie and fans will see how isolation has affected her state of mind.

"Next time we see Bonnie, it's her birthday, and her friends are in the spirit of celebrating her even though she's not with them, putting together a birthday party for her," showrunner Julie Plec told E!Online. "And she's putting together a little thing for herself. But you get to see that sense of isolation and loneliness."

Meanwhile, Enzo, who learned that existence of Sarah Salvatore, Damon and Stefan's great-niece, will enlist a reluctant Matt to help interfere with her life. Although Sarah Salvatore was briefly introduced in the midseason premiere, fans will get to know more about her in the upcoming episode, which will air on Thursday.

Elsewhere, Stefan and Caroline's relationship is going to deepen as he helps her cope with Sheriff Forbes' illness, and Jeremy will contemplate leaving Mystic Falls for good.

Check out the extended promo of "The Vampire Diaries" season 6 episode 13 below: