On the back of this book it says:

Miss Justwright is a respectable lady, who lives in a respectable street with respectable neighbors. Perhaps the only unusual thing about Miss Justwright is her tendency to use her brains. And in the summer in which this book is set, brains are what Miss Justwright needs! Miss Justwright receives an unexpected house guest, but not just any house guest, her visitor is an ancient German. The Great Duff of Leipnir is sadly lacking in manners. As Miss Justwright says, "Why don't you act normally? Life could be so simple if everyone would just act normally!"