Pieces of her / Karin Slaughter.

What if the person you thought you knew best turns out to be someone you never knew at all? Andrea Cooper knows everything about her mother, Laura. She knows she's spent her whole life in the small beachside town of Gullaway Island; she knows she's never wanted anything more than to live a quiet life as a pillar of the community; she knows she's never kept a secret in her life. Because we all know our mothers, don't we? But all that changes when a Saturday afternoon trip to the mall explodes into violence and Andrea suddenly sees a completely different side to Laura. Because it turns out that before Laura was Laura, she was someone completely different. For nearly thirty years she's been hiding from her previous identity, lying low in the hope that no one will ever find her. But now she's been exposed, and nothing will ever be the same again. Twenty-four hours later Laura is in the hospital, shot by an intruder who's spent thirty years trying to track her down and discover what she knows. Andrea is on a desperate journey following the breadcrumbs of her mother's past. And if she can't uncover the secrets hidden there, there may be no future for either one of them.