Brad Sterling, a strapping young man, finds his family life turned upside down when Fit Kitty, his stepsister, introduces him to her wild, free-use fantasies. She leads him on, her lithe body writhing with desire, before surrendering to his throbbing length. Brad, overcome with lust, takes her over and over, their family bond growing stronger with each taboo thrust, their secret encounters becoming a regular, steamy affair.