The second season begins with Elena discovering her uncle John's bloody body and learning Jeremy's fate, and Damon realizing that Katherine has returned. Meanwhile, Caroline is taken to the hospital following a car accident, and Tyler's mysterious uncle Mason arrives in town.

Stefan and Damon decide on a new plan to deal with Katherine at the Lockwood’s masquerade ball. Katherine calls on an old friend, Lucy, to attend the ball with her. Bonnie, Jeremy and Alaric all do what they can to help Stefan and Damon, but Katherine has a surprise planned that none of them could foresee. Things take an ugly turn when Matt and Tyler start doing shots with their friends.

Johnathan Gilbert’s return to Mystic Falls comes as an unhappy surprise to Elena, Jenna and Damon. Caroline lets Stefan know about her conversation with Tyler, and Stefan does his best to reach out to a confused and conflicted Tyler. Jeremy comforts Bonnie after her disturbing conversation with Jonas... When Jules takes a hostage, the situation quickly escalates into a violent confrontation.

Stefan and Damon are furious when they discover that Elena has defied them both to make a new ally and take control of the plan to out-maneuver Klaus. Disagreement over how to protect Elena leads to growing tension between the Salvatore brothers. Meanwhile, Stefan has his hands full trying to keep a confused and frightened Jenna safe. Flashbacks to 1491 reveal Katherine’s introduction to Elijah and Klaus, along with the origin of the moonstone curse. Elena learns shocking new information about Klaus’ motives.

On the morning of Elena’s 18th birthday, Caroline is busy planning a party, but Elena is focused on searching for any clues that might help her discover where Stefan is. Damon is also searching for Stefan, while trying to protect Elena and keep her from doing anything that would draw Klaus’ attention. Meanwhile, Klaus and Stefan are busy trailing a werewolf named Ray Sutton. Now working at the Mystic Grill along with Matt, Jeremy is struggling to understand why he keeps seeing the ghosts of Vicki and Anna since he was brought back to life by Bonnie’s magic. Meanwhile, Alaric does his best to watch over Elena and Jeremy, while dealing with his grief over Jenna’s death. Finally, Caroline and Tyler face a new and unexpected challenge.

On the first day of their senior year, Elena, Caroline, Bonnie and Matt are still reeling from recent events, while Tyler seems to be enjoying everything a little too much. Damon is annoyed by a new houseguest, and everyone is surprised by the arrival of a new student in Alaric's history class. Matt asks Bonnie for help when he realizes he made a serious mistake. Meanwhile, Stefan continues to carry out his latest assignment from Klaus.

Determined to protect his sister, Jeremy makes a decision that will change everything. In the harsh reality of the present situation, Elena longs for simpler times when her parents, Grayson and Miranda, and Aunt Jenna were still alive and her biggest concern was her relationship with Matt. Stefan and Damon leave Mystic Falls together on a mission, but soon split up when Elena needs one of them. Caroline and Tyler are forced to make a life-changing decision. Finally, Bonnie makes a secret deal that has heartbreaking consequences.

Elena tries to cope with the extreme highs and lows that are part of becoming a vampire, and Stefan and Damon almost come to blows while arguing about what is best for her. Damon decides to help Elena in his own way and asks her not to tell Stefan. A stranger, Connor Jordan, arrives in town and begins questioning Sheriff Forbes and Mayor Lockwood. Connor’s actions quickly convince Stefan that they are dealing with a dangerous vampire hunter. Jeremy and Matt are surprised to see a girl they used to know, April, has returned to town and is enrolling at Mystic Falls High. At a town gathering, Elena comes close to losing control until Caroline steps in to help her. Finally, Damon confides his feelings to an unexpected friend.

Terrifying hallucinations leave Elena shaken and confused, causing her to make a dangerous mistake. After giving Stefan some very disturbing news about Elena, Klaus takes matters into his own hands. Professor Shane reveals a story of ancient witchcraft to Damon and Bonnie. With help from Klaus and Stefan, Jeremy begins a new chapter in his life. Finally, Elena makes a painful personal confession to Stefan, and Matt gives Damon startling new information about Professor Shane.

As a Winter Wonderland-themed party fills the streets of Mystic Falls, Stefan and Caroline find themselves at odds with Tyler over his plans for Klaus and his hybrids. When Caroline proposes a solution to their problem, Hayley finds a dramatic way to make it clear that she is not on board. Later, Klaus makes a discovery that leads to chaos and violence. Meanwhile, Elena and Damon retreat to the Gilbert Lake House to help Jeremy conquer some dangerous inner demons with the help of Bonnie and Professor Shane, who reveals a piece of ancient history that leaves them all speechless.

Months after Damon and Enzo mysteriously vanished from the Armory vault, Stefan tirelessly pushes forward with their search, while Bonnie struggles holding onto hope that they will be found. Meanwhile, a dangerous encounter with an unexpected visitor leaves Caroline and Alaric fearing that someone – or something – may be targeting their family. Finally, after following some mysterious clues, Stefan realizes that whatever has a hold of his brother may have a more damaging grip over him than he could have ever imagined.

With the fate of Mystic Falls at stake, Stefan and Damon must fight their greatest enemy for one last battle.