Harper Collins' Detective Story Club imprint is by no means confined to Golden Age detective fiction. Hugh Conway and Anna K. Greene are among the significant Victorian crime writers represented in the series. Another is Emile Gaboriau, creator of Monsieur Lecoq, a prototype of the Great Detective, and a master of disguise.
Richard Dalby's introduction contains useful background .The book was first published as Dossier No. 113 in 1867, and has also appeared in English translation as File No. 113. Apparently this original version ran to a massive 145,000 words. Collins commissioned a new translation by Ernest Tristan, which cut the word cut roughly by half while retaining the essentials of the storyline intact. The abbreviated version was called The Blackmailers, and this is the version of the story that has been reissued.
The story gets off to a very good start. A bank is robbed, and only two men appear to have access to the safe that the criminal(s) broke into. Which of them is guilty? Or has something else happened? The official police detective, nicknamed "the Squirrel", is keen but inclined to follow false scents. Before long, the rather enigmatic Lecoq becomes involved, sometimes in disguise.
After a suspenseful build-up, we then move into an extended flashback which charts events of the past which led up to the crime .Despite the (very wise) decision to cut the story in half, this melodramatic storytelling seems to go on forever, and my interest began to wane. This, the third case for Lecoq, is historically significant, but the structural weaknesses show that authors were still trying to figure out how best to tell a mystery story. Conan Doyle experienced similar difficulties with his own longer stories about Sherlock Holmes, but Holmes is an inherently more fascinating character than Lecoq. But, just possibly, without Lecoq there might not have been a Sherlock Holmes.