Venice, early World War II. To turn their monotonous life as a couple around, English professor Nino Rolfe leaves unattended the key to the drawer of his bedside table, where he hides a diary in which he notes all his fantasies about his wife Teresa. Reading in the notebook all the morbid desires of her husband, the woman a his diary where she confesses all the most forbidden thoughts. The husband and wife thus rediscover passion, but they will go so far that they will have to pay the bitter consequences.