The things 17-year-old Erin Post wants are drastically different from the things she needs. A junior in high school, Erin wants nothing more than to be thin. In reality, she's a depressed girl with a serious eating disorder who needs to stop starving herself. When Erin's mother insists that she see a psychiatrist, Erin runs away to Chicago. There, she meets Lin and Ari, two homeless teens who show her that's there's a lot more to the world...