Atticus Shane's son died in an accident. His wife, the witch Caitlin uses Expression to try and bring him back to life. However she is consumed by Expression and dies as well, about 6 months after her son.
Katherine compels a man to pick a fight with Mason Lockwood. Mason eventually kills his friend and thus triggers the werewolf curse.
It's interesting to learn, from Stevie, that even before Mason had triggered his werewolf curse, he was hanging out with a pack, who did not approve of his relationship with the vampire "Kathy" (Katherine). At this time he began asking questions about the Sun and the Moon Curse.
He filmed the transformation and chronicled his experience in a diary, beginning August 31. that Caroline and Tyler find this diary later.
Elena and Stefan come to a truce with Damon, Bonnie starts using her magic, Caroline and Matt hook up, Jeremy meets Anna. Alaric Saltzman is the new history teacher/vampire hunter.
Damon infiltrates the Founder's Council and befriends Sheriff Liz Forbes. He kills Lexi, Stefan's friend, to gain her trust.
Emily possesses Bonnie and destroys the crystal that would open the tomb. In a fit of rage, Damon almost kills Bonnie. Stefan saves her, giving her his blood.
We learn Damon's "evil masterplan" to open the Tomb under Fell's Church and release Katherine. Stefan proposes to help him, as long as the other vampires stay locked. Bonnie and her grandmother, Sheila agree to help, as long as all vampires inside the tomb are burned.
Katherine is not inside the tomb.
Anna is also working to open the tomb and release her mother.
Stefan discovers that Elena is adopted, and that her real parents are Isobel Flemming and John Gilbert.
Sheila dies as consequence of the spell, and all tomb vampires are released.