Stefan, Damon, Bonnie, Jeremy, Alaric, and Caroline plan to kill Katherine at the Lockwoods' masquerade ball. Katherine is visited by Lucy, a witch who is to help her retrieve the moonstone. Under Katherine's compulsion, Matt fights Tyler. Caroline breaks up the fight, but Sarah, who is also compelled, stabs Tyler, and he accidentally breaks her neck. Tyler's eyes turn yellow, showing that the curse has been triggered. Stefan and Damon try to kill Katherine, but they stop when Jeremy tells them that every time they stake her, Elena is wounded. Katherine reveals that she had Lucy put a spell on Elena and herself, which linked them. Lucy, who is Bonnie's cousin, lifts the spell and incapacitates Katherine, who collapses. Damon traps Katherine in the underground tomb. As Elena heads home she is intercepted by a masked stranger.