Stefan and Damon come to Elena's assistance and, in the process, learn surprising new information.

Elena puts herself in a dangerous position as she searches for the truth about Katherine's past and what her own future may hold. Knowing that Stefan would never agree to her plan, Elena swears Caroline to secrecy. Damon uses a new-found confidant to help him try to discover the real purpose and power of the moonstone. Jeremy and Bonnie meet Luka, a new student with a surprising family history.

Elena decides to take matters into her own hands and offers a tempting incentive to Rose for her help. When things take an unexpected turn, however, Rose calls on Damon to deal with the plan Elena has set in motion. Jeremy's reckless attempt to help Bonnie retrieve the moonstone lands him in a life-threatening position and forces Stefan to put himself in danger. Bonnie and Luka form a closer connection. Tyler shows Caroline the Lockwood cellar, where she makes a discovery that leaves them both terrified.

As the full moon nears, Caroline helps Tyler prepare for his transformation. Meanwhile, Damon and Alaric are suspicious when a stranger shows up looking for Mason.

Stefan and Elena attempt a romantic weekend getaway, not realizing that they've been followed. Damon attends a tea at the Historical Society.

Stefan tells Elena about his darkest days. Trying to catch Elijah off guard, Damon arranges a dinner party.

Katherine's mind games cause everyone frustration, but Elena, Stefan and Damon realise that her knowledge of Mystic Falls' history could be crucial to their survival.

As the students get ready for a 1960s-themed dance at the school, Elena begins receiving disturbing messages from the ancient vampire Klaus from an unusual source.

Stefan and Damon are angry when they find out that Elena has taken matters into her own hands in the battle against Klaus. Tensions also rise between the brothers over the best way to protect her.

Damon reveals that he is willing to go to incredible lengths to protect Elena from falling victim to Klaus's plans. Stefan and Elena spend a romantic day together.

Despite an unanticipated act of courage, events spin out of control in a frightening way.

Lives hang in the balance as the consequences of the sacrifice ritual play out.

Damon, Alaric and Elena reach a hidden cage in the secret tunnel beneath the Lockwood mansion. Alaric studies the runes and primitive pictures, which indicate it was the home of an ancient Viking family, who interacted with the Original werewolf, vampires and witch. They confront Rebekah, who is shocked to tie it up with her memories of her family's youth, when their father Mikael, now the only hunter they truly dread, bullied his sons, especially Niklaus, leading in interaction with the originally friendly werewolf neighbors to family drama and the origin of vampires. After taunting Stefan, Damon releases him from Lexi's 'aversion therapy' and takes him along to seek Mikael's help. Alaric and Elena work out that Rebekah's memories don't take account of a last, crucial cruel twist.

Prophetic dreams about the mysterious fourth coffin lead Bonnie and Elena to a surprising source, while Tyler seeks help to break free from Klaus' bond so he can be with Caroline. Alaric's new friend Dr. Fell has a secret no one sees coming, and Stefan's interference in Elena's life reveals something that surprises even him.

Now Klaus has Elijah back, they host a dinner party to negotiate a future with the Salvatore brothers, who actually procrastinate. Meanwhile combined witchcraft finally opens the mystery coffin, from which a scary surprise guest is released, but both families will be shocked. Alaric has been wounded dangerously by lover Dr. Fell, who happens to be supernatural, which makes saving him problematic, but Elena steps up. Caroline's father Bill Forbes refuses to survive his vampire bite by allowing Caroline to turn him into one like her.

Now Klaus's original family's coffins are open, he's supplanted as family head by their sorceress-maker, mother Esther, who holds a grand ball in their splendidly restored mansion. Invitations with gifts and where needed other persuades go to the Salavtore brothers, Alaric, Matt, Caroline and especially Elena, who is asked for a private meeting. After Stefan prevents Damon from stopping her, she learns that Esther, aided by son Finn, needs Doppleganger blood to put a fatal spell on her children, the others being an 'abomination' except Elijah, firstly binding their fate. Tyler prepares his return.

After starting her day with a startling discovery of Damons' latest indiscretion, Elena is frustrated to find that none of her friends agree with her on how they should react to the Original family's internal power struggle. Once again caught up in the destiny of the Bennett witches, Bonnie and Abby find themselves playing a part in a ritual to appease the spirits of nature. When Elijah gives Damon and Stefan a dangerous ultimatum that puts Elena in danger, they turn to Alaric and Meredith for help with a plan that leads them to a terrible choice.

Determined to protect his sister, Jeremy makes a decision that will change everything; Bonnie makes a secret deal that has heartbreaking consequences.

At a fraternity costume party, Damon gives Elena a lesson in choosing a victim. Klaus reveals an encounter with a group of vampire hunters - flashing back to 12th century Italy.

While in a small town in Pennsylvania with Rebekah (CLAIRE HOLT), Elena has a surprising encounter with Elijah (DANIEL GILLIES). Klaus receives Caroline's reluctant help.

When Caroline's plans for the perfect Senior Prom night are disrupted by Elena, she turns to an amused Klaus for a solution. Bonnie makes a terrifying discovery.

Klaus returns to his past in New Orleans and meets with his former protégé, Marcel (CHARLES MICHAEL DAVIS), a charismatic vampire with control over the city's inhabitants.

Back to Katherine's early life 1490, Nadia helps her mom with a fighting plan.