The character of Ellery Queen was probably initially suggested by the novels featuring detective Philo Vance by S.S. Van Dine, which were very popular at the time. At this point in time, however, Van Dine's sales were dropping and Queen's were rising. This novel was the ninth in a long series of novels featuring Ellery Queen, and the last to contain a nationality in the title. It was the first novel from which an Ellery Queen movie was made, and in the same year as its publication; 1935's The Spanish Cape Mystery with Donald Cook as Ellery Queen and Guy Usher as Inspector Queen omits any nudity and is only moderately faithful to the book.
The introduction to this novel contained a detail which is now not considered part of the Ellery Queen canon. The introduction is written as by the anonymous "J.J. McC.", a friend of the Queens. Other details of the lives of the fictional Queen family contained in earlier introductions have now disappeared and are never mentioned again; the introductory device of "J.J. McC." disappears after this novel.
The "nationality" mysteries had the unusual feature of a "Challenge to the Reader" just before the ending is revealed -- the novel breaks the fourth wall and speaks directly to the reader. This is the final instance of the challenge. "For years now I have been challenging my readers to solve my cases by the exercise of close observation, the application of logic to the winnowed facts, and a final correlation of the individual conclusions ... Technically there are no snags. The facts are all here at this point ... Can you put them together and logically place your finger on the one and only possible murderer?"
"A fair example of the chat and comment that enliven the Queen cases for some and make them a trifle too rich for others.