Glass House People — Kathryn Reiss

Beth's mother, Hanny Lynn, hasn't spoken to her parents or her sister, Iris, in twenty years. But she decides it's time to set aside old grievances, so sixteen-year-old Beth and her brother, Tom, find themselves spending a sweltering summer with their mother and her family in a sleepy Pennsylvania town. More than just homesick, Beth is troubled by deep family tensions and Aunt Iris's sudden drunken outbursts. As Beth begins to delve into family history, she discovers a chilling and inexplicable tragedy.