Step-sister suffers from amnesia and, upon regaining a semblance of her past, she misconstrues her step brother for a lover and has intercourse with him

Half-sister, forgets that she has a boyfriend, looks for sex partner. She fails to recognize her step brother and is welcomed by a huge shock. There is then POV action with repercussions resulting in a rather crazy ending creampie. Teenage pleasures in the great out doors still remain taboo.