Final volume of the second case! After their successful first case, during which the Pik As agency was founded, our two unusual detectives are now investigating the disappearance of a ghost. Indeed, the late 19th century is a tough time. Their client, an Indian from the circus in Lille, has lost all trace of his twin brother, who passed away a few years ago. In fact, he maintained a supernatural connection with his ectoplasm, which is now playing dead. Meanwhile, Auguste Dupin, the astute scientist, is sent from Paris to Lille to uncover a terrible crime.