Kenzie Madison, the cute 18-year-old step-sister, thinks she's alone in the house. She strips naked, climbing onto the bed in a naughty cowgirl position, ready for a solo session. But little does she know, her stepbrother is home early. He catches her, his perverse intentions piqued. Kenzie, embarrassed yet aroused, decides to continue, inviting him to join. He takes her up on the offer, missionary style, their taboo affair heating up. They're both aware they could get caught, but the thrill only intensifies their fucked-up family dynamics.