In a sprawling, dimly lit mansion, four stepsiblings find themselves alone and horny. Jill Taylor and Kimora Quin, the stepsisters, have always had a thing for each other, but when their stepbrothers Nick Strokes and the enigmatic mystery guest join them, they decide to take their relationship to the next level. They start with a threesome, but as the night progresses, they invite the stepbrothers to join in, turning their private fun into a full-blown, taboo swap orgy.