"The Vampire Diaries" star Nina Dobrev will make a crossover appearance in the next all-new episode of "The Originals."

In the upcoming episode, which is titled "Red Door," Dobrev will play a doppelganger named Tatia, whom Klaus and Elijah both fell in love with at one point during their past.

According to executive producer Julie Plec, the crossover will appear in a flashback, she told E! News. She also teased that Tatia's life came to a tragic end when Esther Mikealson killed her in order to use her blood in a spell that prevented Klaus from becoming a hybrid, reports Entertainment Weekly.

"There was a character's name introduced a long time ago in Season 3 in association with Klaus and Elijah and how they became vampires and a girl that they both loved a long time ago who was the original doppelganger, Tatia," said the EP.

Both Klaus and Elijah were in love with Tatia, "so it's a little bit of history repeating itself like with Stefan and Damon," Plec says. "And then Esther, their mother, killed her so that she could make Klaus not a hybrid. There's lots of secrets and scandal and romance and terrible tragedy attached to her character. We'll get to go back into the past to see how that all played out."

Ksite.com also dropped spoilers about the shocking torment that Esther will put Elijah through now that she has him locked up. In the meantime, although Finn doesn't have a lot to do in his new body, he does do something that will put his power on display.

Ksite.com also warned that "There's at least one big shocker within that the audience will not see coming."

According to Dread Central, the official synopsis of "Red Door" reads as follows:

"In order to show Elijah (Daniel Gillies) that her plan is what's best for him, Esther forces him to relive a time long ago when he loved a young woman named Tatia (guest star Nina Dobrev).

"With the help of Marcel (Charles Michael Davis), Hayley (Phoebe Tonkin) is determined to find Elijah, who has gone missing, but is torn when she discovers that Klaus (Joseph Morgan) is also in trouble. Elsewhere, Cami (Leah Pipes) finds herself in a dangerous situation when Mikael (guest star Sebastian Roche) takes her hostage as a way to lure Klaus to him, and Davina (Danielle Campbell) makes an upsetting discovery about Kaleb's (guest star Daniel Sharman) true identity.

"The Originals" season 2 episode 5, "Red Door" airs on Monday, Nov. 3 at 8 p.m. ET on The CW.

Watch teaser videos below.