The Crystal Stopper

Maurice Leblanc's mystery book The Crystal Stopper follows the exploits of gentleman thief Arsène Lupin. From September to November 1912, the novel was published in serial form in the French daily Le Journal. It was then published as a standalone novel. The terrible Panama scandals of 1892 and 1893 served as Leblanc's inspiration. The concept of hiding something in plain sight is taken from Edgar Allan Poe's short story "The Purloined Letter" and used throughout the novel.
Two of Arsène Lupin's associates are detained by the police when a crime is committed during a break-in at the residence of Deputy Daubrecq. Both will get the death penalty, regardless of whether one is guilty or innocent of the crime. Lupin fights against the vicious blackmailer of Deputy Daubrecq, who is holding an incriminating document concealed in a crystal stopper, while he tries to free the victim of a miscarriage of justice.