希芭·哈特(凯特·布兰切特 饰)是学校里新来的美术老师,她年轻美丽,气质高雅。老教师芭芭拉(朱迪·丹奇 饰)悄悄地关注起希芭,并渐渐和希芭结成好友。希芭把芭芭拉当成密友,向她倾诉年迈丈夫的无趣,女儿的叛逆和儿子的低能。两个女人结为看起来温馨又和谐的忘年之交。 无意中芭芭拉发现希芭与学生的不论之恋,她逼迫希芭承认了奸情,并答应保守秘密。可是两个人的友谊却由此变质。保密人芭芭拉对希芭的占有欲越来越强,希芭在秘密被泄露的威胁下一次次屈服。然而秘密总有被泄露的一天,保密人事无巨细的日记转瞬成了记满丑闻的笔记。The bitter, cynical and lonely Barbara Covett is a tough and conservative teacher, near to retirement, who is loathed by her colleagues and students. In the loneliness of her apartment, she spends her spare time writing her journal, taking care of her old cat Portia and missing her special friend Jennifer Dodd. When Sheba Hart joins the high-school as the new art teacher, Barbara dedicates her attention to the newcomer, writing sharp and unpleasant comments about her behavior and clothes. When Barbara helps Sheba in a difficult situation with two students, the grateful Sheba invites her to have lunch with her family. Sheba introduces her husband and former professor Richard Hart, who is about twenty years older than she; her rebellious teenager daughter Polly; and her son Ben that has Down's Syndrome. Barbara becomes close to Sheba, but when she accidentally discovers that Sheba is having an affair with the fifteen year-old student Steven Connolly, Barbara sees the chance to manipulate and get closer to Sheba, hiding the secret from the school headmaster. When Portia dies and Sheba does not stay with Barbara in the veterinary office to see Ben in a theater play, Barbara plots a Machiavellian revenge against Sheba, creating a scandal and consequent turmoil in their lives.