Before I fall asleep

Every morning, Christine Lucas wakes up in an unfamiliar room, next to a stranger. She looks at herself in the mirror and does not recognize her body, because it looks twenty years older. Every morning this man explains Christine that he is her husband Ben, and she suffers from an form of amnesia, in which all the old memories are lost, and the new ones are not preserved. On the advice of a doctor, Christine secretly begins to keep a diary from her husband and writes into him everything that she manages to find out and recall during the day, trying to recreate her past and the fatal case that deprived her of memory. One morning she opens a diary and sees that she wrote three unexpected and terrible words: Do not believe Ben. Suddenly, everything that her husband said seems to Christin is suspicious. What accident caused her condition? Who can she trust? Why does Ben lying to her?