为了让罹患血癌的凯特（苏菲亚·威希涅瓦 Sofia Vassilieva 饰）能够活下去，父母通过基因技术“制造”了与凯特的基因完美配型的小女儿——安娜（阿比吉尔·布莱斯林 Abigail Breslin 饰）。安娜感觉自己只是姐姐凯特的“药罐子”，11年来，凡是在凯特有需要的时候，无论是脐带血还是白血球、肝细胞、骨髓，她都得源源不断的向凯特提供。然而，即使有孤注一掷的妈妈（卡梅隆·迪亚茨 Cameron Diaz 饰）、无可奈何的爸爸，以及身边所有人的爱，凯特的情况还是越来越糟，肾功能的衰竭必须要年仅11岁的安娜捐献出自己的一个肾。这一次，安娜选择了拒绝，并且寻找到律师坎贝尔把母亲告上法庭，她要捍卫自己的身体。然而，法庭上哥哥杰西却吐露了另一番真相…… 　　本片根据美国当代畅销书女王朱迪·皮考特（Jodi Picoult）的同名小说改编。In Los Angeles, the eleven year old Anna Fitzgerald seeks the successful lawyer Campbell Alexander trying to hire him to earn medical emancipation from her mother Sara that wants Anna to donate her kidney to her sister. She tells the lawyer the story of her family after the discovery that her older sister Kate has had leukemia; how she was conceived by in vitro fertilization to become a donor; and the medical procedures she has been submitted since she was five years old to donate to her sister. Campbell accepts to work pro bono and the obsessed Sara decides to go to court to force Anna to help her sister.