Plot summary
It is Bonnie's birthday, and Jeremy doesn't want to celebrate but is convinced by Damon and Elena to do so. The three of them attempt to piece the broken ascendant back together in attempt to send Bonnie a message, but they have a disturbing realization. Bonnie can't take the solitude anymore and is planning to commit suicide. With Kai's help, Jeremy enters the world to try to stop Bonnie, who is in the garage and starting to poison herself with gas from the car. While saying goodbye to her friends via video, Bonnie realizes that she can't give up yet but is too weak to open the garage door and save herself.
Jeremy manages to open the door, and Bonnie survives. Stefan uncovers a secret about his great-niece Sarah Salvatore while Enzo wants to interfere with help from Matt for an alternate motive. Caroline is trying to cope with the hardships in her life, especially her mother's illness, so Stefan keeps a close eye on her. Lastly, Jeremy contemplates leaving Mystic Falls for good and realizes it might be time to move on with his life.
Credits
Adapted from Wikipedia contributors, The Vampire Diaries season 6. HTML formatting and reference markers removed.