An adaptive ending to Wetfly6969's story Surrogate Lovers. A father discovers his daughter is exposing her body through her webcam to just about any boy who wants to check her out. She then admits that she's been having sex with a number of boyfriends, and he is bent on finding out just how far his slutty daughter is willing to go.
Take one lightly-populated overnight express bus, add one alien-controlled human being and a mysterious substance disguised as anti-bacterial soap, stir well, and you've got an orgy, a transformation, and a possible suicide, all-in-one!