The most important personality in all of the Queen works is, of course, Ellery Queen, amateur detective. In The French Powder Mystery and the other early formal detective works, Queen is presented as an almost pure logician, relentlessly examining pieces of evidence, from the small traces of powder on a bookend to the large details of complex social interactions. A descendant of Foe's Dupin and Conan Doyle's Holmes, he is something of an eccentric, has a unique appearance, and is in possession of a vast and esoteric body of knowledge. In the preface to The French Powder Mystery, the reader learns that Ellery, along with his wife, son, and father, Inspector Richard Queen, retired member of the New York Police Department, is now living in a tiny mountain home in Italy, having given up his old profession. (Ellery's wife and son mysteriously disappear in subsequent works.) The novel...