What is the theme in Are You in the House Alone? by Richard Peck?

Fear is the main theme in this story. The emotion of fear plays a crucial role role this story. When Gail received the first note, she began to feel uncomfortable and even dirty. However, fear did not begin to develop until she began getting eerily-timed phone calls with no one on the other end. By the time she received the second note, Gail was fully aware that someone was watching her and had been watching her for some time. Gail's fear level reaches new heights when the stalker screams in to the phone "ARE YOU IN THE HOUSE ALONE?"