Nathan Bronson suspects that his stepsister, Lilly Bell, is kind of nuts. He decides to set Lilly up by letting him borrow his car since she has dressed nice and slutty to ask. Later, Lilly wants to borrow Nathan's credit card. When he tries to say no, Lilly peels off her shirt to show him her tits and offers to let him touch her pussy. Little does Lilly know that Nathan has gotten another step closer to what he wants even as she struts off with his credit card. When Lilly gets home, Nathan finally gets to cash in on his nice guy act when she tries to show off her sexy new outfit for him.

Nathan tries to tell Lilly no when she climbs onto the couch and offers to stroke him off and suck his dick in return for all the nice things he's been doing for her. Secretly, it's what Nathan has been after this whole time. Lilly delivers, giving Nathan a deep throat sloppy BJ. All Nathan has to do is ask to fuck her and she's happy to comply. Turning around on her hands and knees, Lily leans over the couch arm so Nathan can bang her in doggy.

Now that the stepsibs have decided to take their relationship in a sexy new direction, Nathan takes Lilly every way he can think of. He pulls her into his lap so she can ride his big dick. Turning around, Lilly gives it to Nathan in reverse cowgirl as she rubs her own clit until she's moaning. She winds down with Nathan riding above her as she lays on her back eagerly taking his D nice and deep. Nathan starts to lose his load while he's buried inside his sis, then pulls out to finish. When Nathan confirms that Lilly is on birth control, she says she's not but she wants to make a baby with him. That's how Nathan knows he has a psycho stepsister, and that he just got played in his own game.