When a confused and desperate Caroline leaves the hospital and joins her friends at the Mystic Falls Carnival, Damon wants to take immediate action, but Stefan and Elena come to Caroline's defense. Matt is completely mystified by Caroline's behavior, but still tries to tell her about his feelings for her. Meanwhile, Damon has suspicions about Tyler's Uncle Mason (recurring guest star TAYLOR KINNEY) and uses Tyler's volatile personality in an attempt to get Mason to reveal his secret. Upset with everything going on around her, Bonnie takes her anger out on Damon.