(With thanks to Philippe Aurousseau, & Courtesy of Oncle-Archibald.blogspot.fr)

Starting more than hundred years ago, in 1910, this series of “mysterious novels” is one of the great ancestors of Modern Crime Fiction Series. At a time when the booklet format was very widespread, these books were instead large volumes  of 250 to 300 pages. They were  beautifully illustrated by Félix-Pol Jobbé-Duval (1879-1961) and Robert Salles (1871-1929).