The girl from Widow Hills : a novel / Megan Miranda.

As a child, Arden Maynor was swept away while sleepwalking during a terrifying rainstorm. Found alive days later clinging to a storm drain, the girl from Widow Hills was a living miracle. Arden's mother wrote a book. Now a young woman living hundreds of miles away, Arden goes by Olivia. With the twentieth anniversary of her rescue approaching, the media will inevitably renew its interest in Arden. Then Olivia begins sleepwalking again. One night she jolts awake in her yard-- and at her feet is the corpse of a man she knows from her previous life. -- adapted from jacket