Dark Saturday by Nicci French

Frieda Klein, a psychotherapist, is once again stepping on toes when she agrees to talk to a young woman who was convicted of brutally slaying her mom, stepdad and little brother as a teen. Hannah is now incarcerated in a psychiatric hospital that feels like a maximum security prison for lunatics where she has been overly sedated and beaten due to her periods of violence and what others see as a threat. Frieda sees something else, a young woman who has withdrawn from life, and decides to look into reopening the case. As Frieda begins to pick away at the shoddy police work, and talks to the friends who walked away, the father that wants nothing to do with his crazy violent daughter and others who knew young Hannah, some things just don't sit right. As she digs deeper she may uncover some truths that others worked very hard to bury and don't want brought up. Tense and brutal in the true Nicci French style.