As Mystic Falls gets ready for a festival to celebrate the passing of a comet, Vicki continues to recover in the hospital following Damon's attack. Stefan heads to the hospital to try to use his abilities to make Vicki forget who attacked her, but his efforts are cut short by Matt. Meanwhile, at a parent/teacher conference Mr. Tanner tells Aunt Jenna that Jeremy is in trouble and needs immediate intervention.

As Elena tries to ignore Bonnie's warnings about Stefan, Tyler tries to embarrass Stefan by throwing a ball at him. However, his effortless catch and football skills impress everyone, leading Mr. Tanner to let him join the football team. Meanwhile, Elena invites Stefan and Bonnie to dinner in order to try to get the two to know each other, but the night ends up backfiring. Finally, the town is shocked by an act of violence.

Elena asks Stefan to escort her to the town's annual Founder's Party. Vicki gets Tyler to ask her to the party, then accuses him of trying to hide their relationship from his family. Zach reveals a useful family secret to Stefan. At the party, Damon tells Elena a story about the Salvatore family's past, leaving Elena with questions that Stefan refuses to answer. Finally, Stefan takes action to get Damon out of his life for good.

Stefan takes action to protect Elena. Stefan is hopeful that his plan to get rid of Damon is working. Elena and Jenna are concerned about Jeremy’s relationship with Vicki. Stefan decides to reveal parts of his past to Elena. At a fund-raising car wash, Bonnie is surprised by abilities she didn’t know she possessed, and seeks advice from her grandmother. Finally, Elena hears a disturbing story about the Salvatore family from a stranger.

In a flashback sequence, Stefan reveals the Salvatore family history to Elena. Elena demands that Stefan explain the frightening events that have been happening in Mystic Falls. In flashbacks, Stefan explains how his rivalry with Damon began. Back in the present, Damon impulsively takes control of Vicki’s future, and a confused and frightened Vicki runs away. Finally, Sheriff Forbes and Mayor Lockwood take steps to protect the town.

As Vicki’s behavior becomes more dangerous, Stefan tries to help her. Elena tries to convince Jeremy to stay away from Vicki. Caroline gives Bonnie a necklace she took from Damon to wear with her Halloween costume, and when Damon tries to take it back, he is surprised by Bonnie’s abilities. Bonnie discusses the incident with Grams and learns more about her family’s past. Trying to cheer Vicki up, Matt takes her to the high school’s haunted house, but the evening soon takes a terrifying turn.

On his birthday, Stefan is surprised by a visit from Lexi, one of his oldest friends. Still upset by the events at the Halloween haunted house, Elena does her best to stay away from Stefan, but Lexi gives her some unsolicited relationship advice. Elena and Jenna are surprised by a change in Jeremy’s behavior. At Damon’s insistence, Caroline tries to get his medallion back from Bonnie. Finally, Damon’s offer to help Sheriff Forbes has sudden and tragic results.

Jeremy gets a break from the mysterious new history teacher, Alaric Saltzman and introduces Alaric to Jenna. Bonnie is having terrifying dreams about one of her ancestors. Despite Elena’s efforts to smooth things over, Bonnie and Caroline continue to argue over the medallion. When the girls hold a séance to help them decide what to do, the results are stranger than any of them expected. Matt comes to Caroline’s aid when she needs a friend. Damon finally reveals to Stefan the stunning reason he has returned to Mystic Falls.

After reading the journal left by one of the Gilbert ancestors, Jeremy is inspired to return to his hobby of sketching fantasy creatures, a talent he had abandoned when his parents died. Much to the surprise of their friends, Matt and Caroline continue to hang out together. When Sheriff Forbes tells Damon there has been another attack, he offers to track down the killer and learns a startling piece of information about the town’s founding families. Alaric steps in to help during an awkward scene with Jeremy, Tyler and Mayor Lockwood. Stefan and Elena come to a new understanding, but everything changes when Elena accidentally makes a devastating discovery.

Damon takes a trip to Georgia, where he surprises an old flame, Bree and enlists her help to figure out how to open the tomb. In the process, Damon comes face to face with someone who is determined to make him pay for past wrongs. Stefan opens up to Grams in his effort to help Bonnie overcome her fears and accept her powers. While researching his history paper in the public library, Jeremy meets a cute-but-geeky girl named Anna who has her own theories on the folklore of Mystic Falls. When Damon returns from Georgia, Stefan is waiting with news that will change their world.

Damon, Elena and Stefan attend the school dance with a 1950s' theme, where Alaric introduces himself to Damon. Stefan and Damon try to figure out the identity of the new vampire in town, Stefan gives Elena jewelry filled with Vervain to protect her family and friends. To make ends meet Matt takes a job at the Mystic Grill. Ben comes to help Bonnie when he notices Damon is bothering her.

In flashbacks, Stefan and Damon recall the long-ago actions taken by townspeople including their father, Guiseppe Salvatore, and Pearl, leading to the devastating events that caused the rift in their relationship. In the present, Bonnie's date with Ben takes a frightening turn. Elena helps Stefan as he and Damon race to find the missing journal that belonged to Elena's ancestor. Stefan learns the reason behind Alaric's interest in both the journal and the town's history. Damon discovers that an old acquaintance has returned to town with an agenda he understands.

Stefan helps Elena and Bonnie out of a dangerous situation. Jeremy asks Anna to a party in the woods, unaware that she has her own reasons for wanting to meet him there. When Stefan, Damon, and Elena work with Bonnie and Grams to open the tomb, everyone is shocked by what they discover.

Matt and Caroline are surprised by the sudden reappearance of Matt’s mother Kelly. Stefan and Elena are worried about Damon’s new attitude. Damon is asked by Sheriff Forbes to take part in a fund-raising bachelor auction. Alaric discovers shocking secrets from his own past. With help from Jenna and Stefan, Elena is determined to find out everything she can about her birth mother, but the truth may be more than she can handle.

Anna brings a surprising guest along when she pays a visit to Damon. Elena and Stefan go on an awkward double date with Caroline and Matt, but Stefan and Matt find they have some common ground. Jenna reunites with her old friend Kelly, and Jeremy’s relationship with Anna takes an unexpected direction.

When Stefan and Damon make a dangerous new enemy, Stefan suddenly finds himself in a perilous situation. Damon and Elena try to convince Alaric to work with them to help Stefan. Matt is hopeful that his mom, Kelly, may be back to stay. After her car breaks down in a storm, Caroline make a horrific discovery that shocks everyone in town.

While Stefan struggles to control his new situation, Elena and Jeremy are surprised by a visit from their uncle, John Gilbert. Alaric has an awkward talk with Elena about Isobel. At a Founder’s Day event, Stefan displays a rare party attitude and Damon’s attempt to find out why Uncle John has returned to town takes an ugly turn. An incident at the party causes trouble between Matt and Tyler... and the relationship between Matt and his mother, Kelly, reaches a new low. Meanwhile, Elena’s effort to comfort Jeremy falls short and he decides to take matters into his own hands.

At the Founder’s Day Gala, Elena and Caroline compete for the title of “Miss Mystic Falls” against other girls from town, including Tina Fell and Amber Bradley. Elena is happy to have Bonnie back in town, but Bonnie still has issues to work through. John Gilbert attempts to intimidate Damon, but his plan doesn’t have the desired effect. Damon discovers that Stefan is hiding a dangerous secret that could impact everyone in town.

While Stefan struggles to come to terms with his past, both he and Damon reveal parts of their history to Elena, until she finally learns the truth about how they became vampires. Pearl has an ugly confrontation with Johnathan Gilbert. Damon and Alaric try to find a mysterious invention before Johnathan does. The friendship and flirtation between Jeremy and Anna continues to grow.

Isobel returns to town and stuns Alaric with her attitude and her demands that he arrange a meeting with Elena. When mother and daughter finally meet, Isobel refuses to answer most of Elena’s questions, but reveals that she will stop at nothing to find the mysterious invention Johnathan Gilbert has been searching for. Isobel’s dangerous actions lead Stefan, Damon and Bonnie to step in and help Elena deal with the situation.

Founder's Day has finally arrived, and everyone is busy with last-minute preparations for floats and fireworks. Stefan is uncomfortable with Damon's new attitude toward Elena, but Elena is more concerned about repairing her relationship with Jeremy. Jeremy is worried about Anna, but not sure he's on board with her latest plan for the future. While Caroline is enjoying her day as Queen of the celebration, she also tries to help Matt and Tyler get their friendship back on track. Finally, although Damon and Alaric do their best to stop him, Johnathan Gilbert sets a plan in motion that brings Founder's Day to an end amid chaos, destruction and death.