Trixie Belden and the Mystery of the Uninvited Guest

The Bob-Whites are preparing for the wedding of Juliana and Hans, and Trixie is not impressed by the arrival of a younger cousin, Hallie. With the appearance and disappearance of a wheelchair, food, furniture, bicycles and Juliana's engagement ring, Trixie finds herself with a mystery on her hands and the unwanted assistance of Hallie. Trixie's temper is sorely tested, and she tries to evaluate her own behavior as she attempts to decipher the strange behavior of her close friends and family.