25-year-old Jennifer Mills (Anna Chlumsky) lives her life without commitment, relieved that her boyfriend isnt even close to putting a ring on her finger. Nothing like her older sister Mandy (Chelah Horsdal), who married young and settled into family life, Jennifer loves being carefree. But her mother Kathryn (Susan Hogan) sees Jennifers wild ways as a fear of settling down, and hatches a secret plan to take her from playful to parent in just three weeks. When Mandy and her husband plan a three-week European vacation without their three kids, Kathryn convinces Jennifer to help watch them until she can get into town. Jennifer quickly finds out that playing house isnt for kids, and realizes that she must go from cool aunt to strict parent to keep her sisters trust. But with a little help from Will (Warren Christie), the handsome new neighbor across the street, she manages to pull it together to prove to everyone, even herself, that taking responsibility can be rewarding.