"Behind the Green Door" is a psychological thriller novel by author Mildred A. Wirt. The story revolves around a young woman named Penny Parker who is an amateur detective and a journalism student. Penny is an intelligent and curious young woman who has a passion for solving mysteries. In the book, Penny receives a mysterious invitation to a mansion where she is tasked with solving a puzzling mystery. The mansion is owned by the wealthy and reclusive...