Daughter in Threesome with Bf & Mom

As the door closed behind them, Alex felt a pang of guilt. His step-mother's hand slid into his, and his girlfriend's cheek pressed against his shoulder. They walked upstairs, and into his bedroom, where they undressed in the darkness.Suddenly, the lights flicked on. Alex's heart stopped. There they were, his younger sister, her high-school boyfriend, and his step-mother. He froze, unable to move or speak. His sister giggled and pulled his surprised girlfriend into the room, shutting the door behind them.As they undressed, Alex felt a stirring in his pants. His sister and her boyfriend started making out on the bed, their bodies grinding together. His mom began undressing him slowly, her cool fingers tracing his erection under his boxers. She leaned in for a closer look.