Flirty, flaky party girl Maggie (Cameron Diaz) and plain, dependable lawyer Rose (Toni Collette) are sisters, best friends and bitter rivals who seem to have nothing in common but size 8½ feet and some family secrets. After a heart-rending falling out, they accidentally discover they also share a long-lost grandmother (Shirley MacLaine). Together they travel a bumpy road toward making peace with each other and themselves.