The Lost Casket is a mystery novel written by French author F. De Boisgobey and first published in 1881. The story follows the investigation of a missing casket which contains important documents and valuables belonging to a wealthy family. The casket was last seen in the possession of a young woman named Louise, who is found dead under mysterious circumstances. The investigation is led by a detective named Lecoq, who uses his keen intellect and deductive...