Spyhole Secrets — Zilpha Keatley Snyder

After her father dies, a lonely eleven-year-old finds a solution to her grief when she discovers a secret window into another life
Hallie Meredith is furious with God. First, her adored father died in a car accident. As if that weren't horrible enough, Hallie had to move away, leaving school and all her friends behind. Now she and her mother live in a cramped apartment in a stuffy old mansion. The only bright spot is the crack in a boarded-up window in the attic that gives Hallie an unobstructed view of the apartment in the building next door. Hallie knows she shouldn't be up there -- the attic is forbidden territory. And she shouldn't be spying on the beautiful teenage girl with the long blond hair who seems so tragic (and whom Hallie christens “Rapunzel”). And there's Rapunzel's kid brother and their father, who seems unnaturally strict. Morphing into an amateur spy, Hallie is determined to solve the mysteries of this other family. But is the truth about the people next door different from how it appears?
This ebook features an extended biography of Zilpha Keatley Snyder.