We flashed back a bit tonight to Damon and Lexi in the 1970s, as it served as a parallel to the modern day trip Damon took there with Damon and Rebekah.
But just as Damon screwed over Lexi back in the day, Elena went ahead and did the same thing here, stealing the last two known addresses of Katherine from Damon and leaving him in NYC as she went to check them out with Rebekah.
Elsewhere, Bonnie was under the spell of Silas - who looks A LOT like Shane these days - and executed the third branch of the Expression Triangle. She was in trouble and Caroline saved her by killing 12 witches (she also forgot all about it, and about the fact that Jeremy was dead) and now Silas just needs The Cure to destroy The Other Side and live forever.
He ended the episode by blackmailing Klaus to fetch it for him via the white oak.