The old adage proves true: A person can’t truly understand someone until they walk a mile in that person’s shoes. Director Curtis Hanson proves this figuratively and literally in his latest movie, “In Her Shoes.”

Maggie and Rose Feller are sisters who have shared a love-hate relationship all their lives; although they get along as friends, they can’t stand each other as sisters. It seems the only thing the two have in common is their shoe size.

Maggie, played by Cameron Diaz, is the stereotypical pampered-princess party girl who routinely gets drunk and has flings. Rose, played by Toni Collette, is her responsible lawyer sister who has gotten used to bailing her out.

Since Maggie is incapable of thinking beyond who is going to buy her next cocktail, she still lives at home with her father and stepmother. When Rose brings her home from her disastrous class reunion, their stepmother, who harbors a not-so-secret dislike for the girls, throws her out. Out of sisterly love, Rose takes Maggie in.

Maggie’s laziness, free-loading and stealing, however, eventually wear on Rose. When she comes home and finds Maggie in bed with her office partner and boyfriend, Rose throws her out of both her house and life.

With nowhere else to go, Maggie turns to the only other relative she has – her grandmother Ella, played by Shirley MacLaine, whose existence Maggie discovers from birthday cards she never received. Although she first plans to use Ella as a meal ticket, Maggie instead finds someone willing to help her learn to depend on herself.

She finds Maggie a job at an assisted living facility, where she not only earns money, but self-respect with the help of a retired English professor, who helps her overcome her learning barrier. Meanwhile, Rose finds new love and overcomes some social obstacles in her life.

When she receives an invitation to visit Ella, she is shocked to find Maggie living with her. It is up to their grandmother to help the girls reconnect as sisters. Rose needs to forgive Maggie, but Maggie has to understand that Rose knows things about their past, including their dead mother, that Maggie doesn’t.

Although the story loses some of its momentum in the middle, it doesn’t lose its grip on reality. It may begin as a stereotypical story of family having to cope with each other, but it turns away from its fluffy roots to offer a serious and realistic look at sibling love and rivalry, as well as family coherency on many levels.

It doesn’t matter that Maggie annoys Rose; what matters is that she is Rose’s sister, and that is enough to want to protect her, no matter how much each may grate on the other.

“In Her Shoes” could fall into the trap of chick-flick sentimentality, but it is emotional without being sappy. Coupled with superb performances from Diaz, Collette and MacLaine, “In Her Shoes” is one movie the audience will want to try on for size.