Teenager Olivia Danvers knows that the previous residents at 16 Olcott Place moved out in the middle of the night, but nobody really knows why; the new family, the Donahues, have three children including a daughter, Janie, Olivia's age, and the two become close friends--but when the threatening letters start arriving from the "Sentry of Glennon Heights" the two girls realize that the house and town are hiding sinister secrets, which could tear their...