Irresponsible party girl Maggie (Cameron Diaz) is kicked out of her father's (Ken Howard) and stepmother's (Candice Azzara) home, where she lives for free, and is taken in by her hard-working sister, Philadelphia lawyer Rose (Toni Collette). After Maggie's disruptive ways ruin her sister's love life, Rose turns her out as well. But when their grandmother, who they never knew existed, comes into their lives, the sisters face some complicated truths about themselves and their family.