You've always fancied your step-sister. You know it's wrong but it's not your fault your dad got with her mum. You've always wanted to fuck her. You find your self spying on her as she's naked in the bathroom but you slip up and get caught! She is not happy and insists she gets to see your cock so it's fair. She encourages you to wank it and then allows you to push her against the sink and fuck her quickly before mum arrives home ..