Before I Go to Sleep: S. Watson

Memories define us. So what if you lost yours every time you went to sleep? Your name, your identity, your past, even the people you love-all forgotten overnight. And the one person you trust may be telling you only half the story. Welcome to Christine's life. Every morning, she awakens beside a stranger in an unfamiliar bed. She sees a middle-aged face in the bathroom mirror that she does not recognize. And every morning, the man patiently explains that he is Ben, her husband, that she is forty-seven-years-old, and that an accident long ago damaged her ability to remember.
In place of memories Christine has a handful of pictures, a whiteboard in the kitchen, and a journal, hidden in a closet. She knows about the journal because Dr. Ed Nash, a neurologist who claims to be treating her without Ben's knowledge, reminds her about it each day. Inside its pages, the damaged woman has begun meticulously recording her daily events-sessions with Dr. Nash, snippets of information that Ben shares, flashes of her former self that briefly, miraculously appear.
But as the pages accumulate, inconsistencies begin to emerge, raising disturbing questions that Christine is determined to find answers to. And the more she pieces together the shards of her broken life, the closer she gets to the truth . . . and the more terrifying and deadly it is.