Sam Dawson (Sean Penn), a man with a developmental disability, lives in Los Angeles, works at Starbucks, and is the sole guardian of his six-year-old daughter Lucy (Dakota Fanning), after her mother abandoned them. Despite his limitations, Sam is well-adjusted and has a supportive group of friends with developmental disabilities, as well as a kind, agoraphobic neighbor Annie (Dianne Wiest) who takes care of Lucy when Sam cannot. Though Sam provides a loving and caring environment for precocious Lucy, she soon surpasses his mental ability. Other children tease her for having a "retard" as a father, and she becomes too embarrassed to accept that she is more intellectually advanced than Sam. In preparation for a custody case, a social worker turns up at Lucy's birthday party and takes her away, allowing Sam two supervised visits per week.
On the advice of his friends, Sam approaches a high-powered lawyer, Rita Harrison (Michelle Pfeiffer), whose brusque manner, fast-paced schedule and difficult personal life have earned her a reputation as cold and unfeeling. In an attempt to prove to others that she isn't heartless, Rita surprisingly agrees to take on Sam's case for free (pro bono). As they work together to secure Sam's parental rights, Sam unwittingly helps Rita with her family problems, including encouraging her to leave her philandering husband and repairing her fractious relationship with her son.
During the trial period, Lucy is ...
