Inspector Hanaud is a member of the French Sûreté. He is said to have been the model for Agatha Christie's Hercule Poirot, as well as the opposite of Conan Doyle's Sherlock Holmes. The Affair At The Semiramis Hotel (1917), a novella, is the second Hanaud mystery. Did the robbery/murder really happen or was it the mescal-induced hallucination of the witness? The first novel is At The Villa Rose (1910). The third is The House Of The Arrow (1924) (there are seven through 1949, available at project gutenberg Australia). In 1910, Mason undertook to create a fictional detective as different as possible from Sherlock Holmes, who had recently been resuscitated after his supposed death by Arthur Conan Doyle in 1903. Inspector Gabriel Hanaud was stout, not gaunt like Holmes; a professional policeman, not a gentleman amateur; from the French Sûreté, not Victorian England; and relying on psychological insights rather than physical evidence. His "Watson" is a retired London banker named Mr. Julius Ricardo. - Summary by David Wales
