VD, S3-E18: The Murder of One

Our heroes in Mystic Falls schemed well enough to kill Finn this week, but Bonnie was pressured by Klaus right beforehand to reverse the Original linking spell. As a result, Finn died by his siblings did not.

HOWEVER, Sage also perished because it was discovered that when an Original dies, all of those in his/her bloodline also dies, which is a major problem for Damon, Caroline, Stefan and even Tyler. How can they kill an Original without first knowing his/her bloodline? They could kill themselves if they guess wrong.

The episode ended with Stefan confronting Elena about her feelings for Damon, and her admitting she didn't know what she felt.

And also with Alaric realizing he misplaced his White Oak stake. Well, he didn't misplace it. His psycho killer alter ago apparently took it.

Source: TV Fanatic