Tracey is hot for Jeff, unfortunately he is her best friend's boyfriend and she doesn't want to screw that up. It doesn't make it easier that he's in love with Madge, it doesn't make it any easier that Tracey is living with Jeff and Madge after breaking up with her own boyfriend. And it certainly doesn't help that she can hear them having great sex every night.
She learns that the relationship Madge and Jeff have isn't what she thought. They have sex with other people, and it makes them happy. Then Madge tells her that she wants to tie her up and give her to Jeff as a birthday present. She wants her to be his sex slave for a weekend. The idea is intoxicating and accepting pushes her into the wildest sex of her life. But when it's over, she has the rethink what she wants from life.
