For her brother, Tim, Ginny is a constant source of annoyance. She's always getting in the way of his magic acts, ruining them by revealing the secrets behind his tricks. One day, Tim is given two invitations to see his magician idol, Amaz-O, live on stage. However, due to the show's late time, his mother refuses to let him go. Not deterred, Tim attempts to sneak out of the house, but not before being caught by Ginny. Ginny forces Tim to take her along to the magic show, or else she'll tell on him. Reluctantly, Tim agrees.
At the show, Tim finally gets to meet his idol in person. To his excitement, Amaz-O offers Tim a chance to be his assistant in a disappearing act. Eventually, Tim is brought on stage, where he falls through a trapdoor to the basement. Hoping to talk with Amaz-O, Tim approaches his dressing room, but is taken aback when the magician snaps at him to beat it. In response, the heartbroken Tim decides to steal Amaz-O's magic kit, but things soon go awry. The tricks inside all seem to have a mind of their own. Things go from bad to worse when Ginny is transformed into a rabbit thanks to a magic carrot. Tim tries his best to fix the problem, but nothing seems to work. Out of options, Tim heads back to confront Amaz-O. The magician tells him that Ginny's transformation will wear off soon enough. The book ends with Tim as Amaz-O's new assistant, now a rabbit himself.
Ginny loves making her brother miserable. She's always threatening to tell on him, and loves to ruin his magic acts. She seems to have an interest in Karate, which she uses to beat up her brother. One of her favorite things to do is flick her brother's nose. However, Ginny's behavior is never seen as wrong by her parents. In the television adaptation, she doesn't take any interest in karate.
The book describes Ginny as having wavy blond hair, with hazel eyes.