As Halloween draws near, Vicki's behavior becomes more dangerous which leads Stefan to try to help her control her blood-lust. Elena tries to convince Jeremy to stay away from Vicki, but Jeremy naturally refuses to listen. Meanwhile, Caroline gives Bonnie a necklace she took from Damon to wear with her Halloween costume for the annual costume party, and when Damon tries to take it back, he is surprised by Bonnie's abilities to repel him. Bonnie discusses the incident with her grandmother and learns more about her family's past as voodoo witches. Elsewhere, Matt tries to cheer up Vicki by taking her to the high school's haunted house, but the evening soon takes a terrifying turn when Vicki finally embraces her newfound vampire thirst for blood.