When Nancy runs into former classmate, Karen Phillips, she sees her steal jewelry in a department store. She pursues Karen and discovers that she is constantly watched by a private detective hired to keep her out of trouble. Karen is now a famous tennis star and Nancy is hired in the detective's place to watch over her during an important Las Vegas tournament. When her cover as a sportswriter is blown, Nancy pretends to be the date of famous tennis champion Sandor Castelli. And the make-believe "love match" starts turning into the real thing, Nancy finds herself caught in the volley of danger as the finals turn into what could be the pretty detective's last game.