Good girl bad girl / Michael Robotham.

A girl is found hiding in a secret room in a house being renovated after a terrible crime. For weeks, she has survived by sneaking out at night, stealing food for herself and two dogs that are kept in the garden. The nurses at the hospital where she is taken call her "Angel Face" because she won't tell anyone her name, or her age, or where she came from. Maybe she is 12, maybe 15, or somewhere in between. She doesn't appear on any missing person's file, or match the DNA of any murder victim. Six years later, still unidentified, the same girl is living in a secure children's home with a new name, Evie Cormac, when she initiates a court case demanding the right to be released as an adult. Psychologist Cyrus Haven is sent to interview Evie and decide if she's ready to go free, but Evie Cormac is unlike he's anyone he's ever met. She's damaged, destructive, and self-hating, yet possessed of a gift, or a curse, that makes her both fascinating and dangerous to be with - the ability to tell when someone is lying. Soon, he is embroiled in her unique and dangerous world, his life in utmost peril.