Before I Go to Sleep by S.J. Watson is a thriller that uses the protagonist's amnesia to keep the reader guessing throughout the novel. Set in London, Watson's story focuses on Christine Lucas who struggles with her memory. As an amnesiac, she cannot remember her former life, struggling to recall details from the past fifteen years. She routinely visits a therapist, Dr. Nash, and he suggests that she record her thoughts and feelings in a journal, but she also decides to keep it a secret from her husband, Ben. Later, she is startled to find a warning from herself within its pages, "Do not trust Ben." Much of the plot revolves around Christine's struggles to resolve the natural resulting fear from her condition and her continued unease from her distrust of her husband. The novel has a shocking, climactic twist, which challenges everything that Christine thought she knew about herself and her marriage.
*I wasn't sure if you wanted more information about the outcome. Send me a message if you want more specifics on the ending--I didn't want to include too many spoilers.