Paris 1899. Someone has stolen the wheels off the carriage of Le Compte de Valloire. They have also taken the wheels off the bicycle of Mimi La Sardine. In Bordeaux the direction of road signposts has been changed around: they all point the wrong way. The chief of the Bureau for Lamps, Lampposts and Signposts, Hercule Quincompoix sends his English assistant to investigate. A tale of hilarity and mischief in the City of Light during La Belle Époque, as Herbert Dedwick gets on the trail of the villains.