When "The Vampire Diaries" star Nina Dobrev stopped by MTV News last week, she warned that the season finale would be full of "cliffhangers, deaths and blood." The girl wasn't kidding.

Thursday's finale featured nonstop twists and turns, including the deaths of three characters and the return of a very unexpected one, Katherine.

Elena, Stefan and Damon joined the rest of Mystic Falls to celebrate what they thought would be a worry-free Founder's Day (apparently, they don't watch this show). As Damon put it, for once, there wasn't a looming threat, especially since Bonnie had deactivated the device aimed at killing vampires. What could possibly go wrong?

The answer: everything -- especially since Bonnie lied about working her magic on the device, which was now in Johnathan Gilbert's very untrustworthy hands. Of course, Uncle John already had a plan in motion to use the device (which emits a sound that paralyzes vampires) on the vengeful tomb vamps, who were plotting to attack citizens on Founder's Day. The fact that it would also hurt Stefan, Damon and Anna would just be icing on the cake.

Speaking of Anna, she was upset over her mother's murder and tried to convince Jeremy to transform into a vampire and leave town with her. Jeremy wasn't really having it, but Anna gave him a vial of her blood anyway, just in case. She left slightly dejected and stumbled upon the vampires planning the Founder's Day attack. For a second, it seemed like she was going to join their cause. Instead, she rushed off to warn Damon about their plot. Before he could do anything, though, the piercing sound went off.

Damon. Stefan. Anna. They all went down. Then, much to his own surprise, Mayor Lockwood also fell prey to the sound. Same for his son Tyler, who happened to be driving Matt and Caroline at the time and crashed the car. Tyler surprisingly walked away without a scratch (though his eyes looked plenty weird when the paramedic checked his pupils), but Caroline landed in the hospital in serious condition.

In the meantime, the police gathered up the fallen vamps (Alaric managed to rescue Stefan right in time) and locked them in a basement. The plan? Burn them. Luckily though, Stefan and Elena figured out where they were being held. John tried to stop Elena from going in, but she confronted him about being her father and forced her way through. Still, there was the small problem of the fire, which would be too much for Stefan to take on. That's where Bonnie came in and used her powers to calm the fire so Stefan could rescue Damon. He was OK, but the same couldn't be said for the mayor or Anna, who'd met the wrong end of John's stake.

Later, Elena, reassured Stefan that he was the only man for her, though she was relieved Damon was all right. Meanwhile, Damon went off to see Jeremy and, in a moment of true humanity, broke the news that Anna was dead. Distraught, Jeremy asked Damon if vampires could truly turn off their feelings and whether life was better that way. Not realizing the effect of his answer, Damon said yes. Next thing you know, Jeremy is downing Anna's blood and a bottle of pills.

As he left the house, Damon ran into Elena and continued to reveal his vulnerable side. The two exchanged countless deep looks and before we knew it, they were locked in a passionate kiss that left our jaws practically unhinged. It was interrupted though, as Elena's aunt summoned her indoors, leaving Damon on the porch looking as shocked as we felt.

Inside, Elena headed toward the kitchen where she found John. The two had a heated conversation and suddenly Elena morphed into something darker, something more devious, and we realized this wasn't Elena we were dealing with ... it was her "dead ringer" Katherine. John realized it too, seconds before she stabbed him with a knife.

What did you think of last night's "Vampire Diaries"? Share your thoughts in the comments.