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.