Everyone is concerned about Elena’s new outlook; Rebekah receives unwanted advice from Damon as they continue to search for the cure; Klaus uses Hayley to get the information he wants and makes an interesting discovery.
Caroline worries about Elena’s state of mind; Damon gives some somber news to Rebekah and is surprised at her reaction; Bonnie reveals the rest of Shane’s plan.
Damon runs into one of the five hunters on the island; Stefan makes a confession to Elena; the stakes change for everyone after new information about the cure is revealed.
Shane leads an expedition to a mysterious island near Nova Scotia, where he believes he can locate a cure. Back in Mystic Falls, Tyler confronts Klaus, which leads to violence that involves Caroline.
Klaus turns to Stefan for help; Bonnie receives an unexpected visit and has a frightening run-in; Elena reveals her plan to Stefan.
Klaus tries to control Jeremy by putting Matt in danger; Rebekah looks for a new ally; Bonnie has questions for Shane; Elena negotiates for Jeremy’s safety.
Rebekah appears at Mystic Falls High unexpectedly and elicits a shocking piece of information from Elena; Professor Shane reveals too much to the wrong person; Caroline tries to comfort Tyler.
A winter-theme party is held in Mystic Falls, but amidst the celebration chaos brews when Stefan and Caroline disagree with Tyler over his plans for Klaus and the hybrids. Meanwhile, Klaus makes a discovery that leads to violence; and Elena and Damon go to the Gilbert lake house to help Jeremy conquer some dangerous inner demons.
Amy takes ill and Sheldon becomes her nursemaid, while Wolowitz takes a fishing trip in order to bond with his father-in-law.
Stefan believes a stranger in town who questions the sheriff and the mayor is actually a vampire hunter. Meanwhile, Elena tries to cope with the extreme highs and lows that are part of being a vampire; and Jeremy and Matt are surprised to see a girl they used to know enroll at the high school.
The fourth season begins with Elena waking up after her car accident and realizing she died with vampire blood in her system. Now, she must go through the horrible transition to become a vampire or die. Meanwhile, Bonnie tries to change Elena’s fate and pays a terrible price for it.