Her mom's remarriage has been hard on fifteen-year-old Shelby. Step-dad Roger is strict and treats her like a child. At least they're letting her go to her first boy-girl party. That is until she gets home from school and finds that Roger has changed his mind--he wants Shelby to babysit her year-old brother Josh. It's so unfair! Fuming, Shelby takes Josh in his stroller to the park. After all, it's not his fault. Someone sets off fireworks, distracting...