When Dupin finds a suspicious hair at the crime scene, and places an advert in the newspaper asking if anyone has lost an "Ourang-Outang," things take an unexpected turn. In The Mystery of Marie Roget, Dupin and his sidekick undertake to solve the murder of the beautiful young woman who works in a perfume shop, whose body is found floating in the Seine. The Purloined Letter, the final story, finds Dupin engaged on a matter of national importance: a highly compromising letter has been pilfered from the Queen’s private drawing room. The police know who the unscrupulous culprit is, but they can not find the letter, and therefore are unable to pin the crime on him. It it is up to Dupin to solve the case—which he does, with characteristic flair. A master of rational deduction and intellectual insight, and protoype for Holmes and Poirot, Dupin sees things for what they are, rather than what they appear to be.
"Where was the detective story until Poe breathed the breath of life into it?" —Arthur Conan Doyle