She and her twin sisters Katie and Amanda Zinmen, along with their friend, Harrison, and the twins doll Mary-Ellen, see a ventriloquist act starring teenage Ventriloquist Jimmy O'James, and his dummy Slappy. One day, Slappy shows up at the Zinmen house, and Jillian takes care of the dummy, she often gets annoyed when her twin sisters talk about Mary-Ellen, because that's all they talk about. For the past few days, there have been some cruel pranks around the house, like finding Jillian's pet lizard in Slappy's mouth, she asumes the twins are responsible.
One night when the siblings invite their friend's Harrison and Eddie over, and they discover that Slappy is alive as he drags Eddie across the floor, "This is My Party Now! Slappy screamed, "I Want My Bride!" Jillian gives him Mary-Ellen, but Slappy knocks it away, and says that he wants Jillian to be his Bride, Mary-Ellen comes to life and reveals that she was the one who brought Slappy to life, and she tries to convince Slappy to be her husband, he refuses, then the doll and dummy fight, Slappy pushes her in a saw, and she pulls him in and they both get sliced up in pieces. In the end, Jillian hopes that Slappy is gone forever, but then, Slappy's spirit possesses Jillian, her eyes turn green and she has Slappy's voice.