When their dad takes a job in Japan, 16-year-old live-wire Holly Tyler ends up moving in with her strait-laced 28-year-old sister Valerie Tyler in New York City. Just when Val thinks she's got the perfect life - a promising career in public relations, a handsome and free-spirited boyfriend, Jeff, and her own Upper West Side apartment - everything in her neatly regimented life starts to unravel the minute Holly stumbles through the door.