Conceived by means of in vitro fertilization, Anna Fitzgerald (Abigail Breslin) was brought into the world as a savior sister at the informal suggestion of Kate's doctor, Dr. Chance (David Thornton) (a formal suggestion would have been a violation of legal and medical ethics). She is a genetic match to her older sister, Kate (Sofia Vassilieva), who suffers from acute promyelocytic leukemia, and Anna can therefore donate compatible organs, blood, and tissue to help her sister. Her family members are introduced one by one, and each tells about how Kate's illness has affected them personally. When Kate turns 15, she goes into renal failure and 11-year old Anna knows that she will be forced by her parents to donate one of her kidneys. She also realizes that she may not be able to live the life she will want to lead – she won't be able play any sports, drink alcohol, or be a mother in the future. Anna tells her parents that she does not want to be a donor and proceeds to sue them for medical emancipation and the rights to her own body. Her father Brian (Jason Patric) sees Anna's point, though her domineering mother, Sara (Cameron Diaz), who leads an obsessive campaign to keep Kate alive, is indignant at Anna's decision when she receives the notice of court proceedings. Attorney Campbell Alexander (Alec Baldwin) agrees to work for Anna as her guardian ad litem, suing for partial termination of parental rights. It is later learned he agreed to take the case – not for the notoriety, but because he suffers from epilepsy, and is genuinely sympathetic to her predicament because he also understands how it feels to have no control over his body. Both Sara and Alexander tell their side of the story to the judge (Joan Cusack), who had recently lost her young daughter, something Sara inadvertently mentions. To Sara's dismay, the judge decides against summary dismissal, and the case goes to a hearing.
The film is interlaced with flashbacks that detail Kate and Anna's close relationship, as well as how Kate's illness has affected her siblings' lives and their relationships. In a flashback, Kate also meets a fellow cancer patient, Taylor Ambrose (Thomas Dekker), whom she begins dating. After a date, they kiss outside Kate's house, with Sara and Kate's father Brian watching from their bedroom window. After this, he becomes her boyfriend in and out of hospital and supports her as she undergoes treatment. He then asks her to the hospital's "prom" for teen patients; there, they slow-dance, then proceed to a vacant hospital room. A few days later, Kate begins to worry as she has not seen Taylor since the dance. In anger, she reveals to Sara that they made love. Kate subsequently learns that Taylor has died and later attempts suicide by overdosing on painkillers, but Anna stops her. Kate later expresses hope that after she dies, she will see Taylor wherever she ends up.
Kate makes a request to go to the beach one last time. Brian obtains permission and compassionate encouragement, from Dr. Chance, who claims she is "no more sick there", to do so. Brian discharges her from the hospital for the day and takes her and the kids to the beach. When Brian arrives home to pick everyone up, Sara overreacts and demands that Kate be returned to the hospital immediately, arguing that bringing her to the beach is effectively "killing her". Brian angrily refuses and drives off, threatening Sara with a divorce if she does not join them. Sara shows up at the beach, where they enjoy one final family outing.
During the hearing, Anna and Kate's brother, Jesse, reveals while Anna is on the witness stand that Anna is actually acting under Kate's instruction; Kate, not wanting to live any longer and be a detriment to her family, had gently persuaded Anna to refuse to donate her kidney, knowing that Sara would be too narrow-minded to listen to her. It also emerges that Anna had wanted to give Kate her kidney of her own accord, and had been terribly upset at Kate's decision. Sara is indignant and attempts to argue, but is finally forced by both Jesse and Brian to realize that Kate had been trying to tell her she is ready to die for some time. The judge makes a request to visit Kate in the hospital before finalizing the case. Later that day, as the remainder of the family leave, Kate gifts her mother with a memory book she has made over the years and later dies while sleeping at the hospital with her mother by her side. After Kate's death, Campbell brings the court decision: Anna won the case. The family moves on with their lives. Sara, who gave up practicing law to look after Kate returns to work, Brian retires from firefighting and counsels troubled youths, and Jesse receives an arts scholarship in New York. Anna reveals that every year on Kate's birthday they go to Montana, which was her "most favorite place in the world". Anna concludes that she was not born merely to save her sister, she was born because she had a sister, and that their relationship continues even in death.
Upon the original creation of the film adaptation, sisters Dakota Fanning and Elle Fanning were cast to play Kate and Anna respectively. However, when Dakota heard that she would be required to shave her head for the role, she dropped out of the film as then did Elle. The two sisters were replaced, with Abigail Breslin taking on the lead role as Anna Fitzgerald and Sofia Vassilieva on the role of Kate Fitzgerald.Abigail Breslin as Anna Fitzgerald, Kate and Jesse's younger sister.
Cameron Diaz as Sara Fitzgerald, Kate, Anna and Jesse's mother, Brian's wife.
Sofia Vassilieva as Kate Fitzgerald, a young girl suffering from Leukemia. Sister to Anna and Jesse.
Olivia Hancock as Young Kate Fitzgerald
Jason Patric as Brian Fitzgerald, Kate, Jesse and Anna's father, Sara's husband.
Chris Kinkade as Dr. Nguyen
David Thornton as Dr. Chance
Evan Ellingson as Jesse Fitzgerald
Brennan Bailey as Young Jesse Fitzgerald
Paul Christopher Butler as Three-year-old Jesse
Alec Baldwin as Campbell Alexander
E.G. Daily as Nurse Susan
Lin Shaye as Nurse Adele
Joan Cusack as Judge De Salvo
Heather Wahlquist as Aunt Kelly
Thomas Dekker as Taylor Ambrose
Emily Deschanel as Dr. Farquad
Jeffrey Markle as Dr. Wayne
Amit Khanduja as Chief in staff Surgeon
The film received mixed reviews from critics. Rotten Tomatoes reports that 47% of reviews for the film were positive, based on 126 reviews. Another aggregate review site Metacritic reported 51% positive reviews based on 28 reviews.
In its opening weekend it placed 5th with a total of $12,442,212, behind Transformers: Revenge of the Fallen, The Proposal (second weekend), The Hangover (fourth weekend), and Up (fifth weekend). The film left theatres on October 8, 2009 with a domestic total of $49,200,230 with a further $46,459,927 from foreign markets. It has grossed $95,660,157 worldwide.
Trailer:Vega4 – "Life Is Beautiful"
TV spot:James Blunt – "Carry You Home"
Plain White T's – "1, 2, 3, 4"
Tyrone Wells – "More"
Movie:Don Ho – "Tiny Bubbles"
E.G. Daily – "Life Is Just a Bowl of Cherries"
Priscilla Ahn – "Find My Way Back Home"
Jimmy Scott – "Heaven"
Regina Spektor – "Better"
Jonah Johnson – "With You"
Greg Laswell – "Girls Just Want to Have Fun"
Pete Yorn – "Don't Wanna Cry"
Phil Xenidis – "Kill Me"
Jeff Buckley – "We All Fall in Love Sometimes"
Edwina Hayes – "Feels Like Home"
Hana Pestle – "These Two Hands"