a brother brings his friends from college and his sister is ursula

The story of a middle-aged woman with small children whose life is shaken up when two free-spirited twenty-somethings move in across the street.

While searching for their estranged mother, two beautiful sisters, Dagmar and Ursula, arrive at a luxurious seaside hotel. At the same time, a mysterious killer starts murdering promiscuous women in the area.

While in a park, a young woman sees her fiancé being quite affectionate with another woman. When she calls him on the telephone to demand an explanation, he tells her that it was his sister. She is not satisfied, and insists on coming over to meet his 'sister'. As the young man broods over how to get out of trouble, an old college friend comes over, and he offers to pretend to be the sister. At first this works, but soon it has created even more complications.

Bobby is a college freshman and as part of a fraternity prank, he poses as Roberta and becomes pledged into a sorority. There he falls madly in love with Diana. As the game escalates, Bobby finds it increasingly hard to keep his twin identities separate...