The story is about the Fitzgerald family. The parents of the siblings are Sara and Brian Fitzgerald and their daughter Kate Fitzgerald has suffered from leukemia for a long period of time. Kate's health is not improving and Brian and Sara are desperate to help her. As a result of Kate's decreasing health, Sara and Brian decide that they will have another child with the specific purpose of their new child being compatible for blood and organ transplantation to Kate. As such, Anna Fitzgerald is born and for many years she was happy to give whatever she could to help her sister's deteriorating health.
However, when Anna turns 13 and Kate needs a kidney from Anna to continue to live, Anna declines. Anna's mother, Sara, is furious at this as she wants Anna to give her kidney to Kate. Anna seeks a lawyer who is able to get her medical empanciation from her parents. Anna meets Alexander Campbell who takes on Anna's case as it will provide him with further publicity. A legal; battle ensues between Sara and Alexander Campbell (acting on behalf of Anna).
Meanwhile, Anna and Kate's brother Jesse, frequently causes trouble and sets fire to buildings. It is clear from the storyline that he is neglected by his parents due to them being focued on Kate and has spent most of his life being shunned away. However, Jesse recovers from this phase and it is clear that his parents do not love him any less but are just constantly focused on Kate because she needs their attention and help.
In the end, Anna is given medical emancipation via a court of law and Alexander Campbell is given power of attorney over Anna's medical affairs. However, as Alexander drives Anna home, they collide with another car and have an accident. Anna is severely injured and is taken to hospital. The doctors inform Brian and Sara that Anna is brain-dead and will not be able to recover. Alexander Campbell then steps in and offers Anna's kidney to Kate as he has power of attorney to do so. Anna's life machine is switched off and her kidney is successfully transplanted to Kate, who manages to live for a few more years as a result of the transplantation.