This just in: Elena Gilbert will turn into one of the undead on The Vampire Diaries Season 4 premiere. This much we know.

Many questions surround this change, of course: How will she react? What will she remember about Damon? Will she still want to be with Stefan?

Klaus at the Door

But the most significant development from the third season finale will also impact Klaus, who Vampire Diaries producer Julie Plec has already promised will be alive and sort of well when the show returns in September.

"The loss of the doppelganger is gonna be a BFD for Klaus and will drive his actions for the season," Plec tells TV Guide. "Suddenly he's vulnerable for many reasons. There's a stake that can kill him, a witch that can desiccate him, and no way to build up the hybrid army he needs - psychologically, at least - to feel safe. Plus, Caroline's going to be peeved at him once she realizes he bamboozled her. In other words, he ain't gonna be so happy."

Read through more spoiler scoop in the TV Guide Mega Buzz now and then vote: Are you glad Klaus is still alive?