Since a severe head injury 17 years ago, forty-something Christine Lucas has had amnesia. She's lost all her long-term memories, and short term recollections from any given day are wiped out when she sleeps. So Christine wakes up each morning not knowing where she is, not recognizing her husband, and thinking she's still a young woman. And every morning Christine's husband Ben has to remind her who he is, tell her about her life, show her a scrapbook with photos, etc.
Unknown to Ben - who feels Christine has seen enough doctors - she is being treated by Dr. Nash, a specialist in amnesia. Dr. Nash has advised Christine to keep a journal, where she records what happens each day. Every morning Dr. Nash calls Christine, tells her who he is, and reminds her to read the journal. This helps Christine put together pieces of her life and gives her some day to day continuity.
Dr. Nash has also been taking Christine to places she's lived, in the hopes of reviving old memories. And Christine does get flashes from the past which she faithfully records in her journal - along with mundane day to day occurrences. As Christine begins comparing her journal to things Ben tells her, she realizes Ben is lying about important matters. As the story unfolds the reader slowly learns the truth about Christine's past as well as what's going on in her life now.
The book has an interesting premise. However, it's very slow moving and tediously repetitive as Christine constantly relearns aspects of her life. Thus this 'thriller' isn't that thrilling, though there's some excitement as the story approaches it's climax - and Christine confronts difficult truths.
From the buzz around the book I expected to like it better, but it was just okay.
Note: The movie adaptation of the book, starring Nicole Kidman (Christine) and Colin Firth (Ben) is half-faithful to the story. It's not a great film (2 stars for me) but it does zip along much faster than the book.