Walter
 This volume is set in a stock historical setting: Paris in the late 19th century. Although it uses the same main characters (Lapinot, Richard, Titi) and gives them the same type of personality, this story bears no relation to the continuing storyline of the volumes taking place in modern Paris. The plot mixes the mystery, horror, and science fiction genres. A giant monster is seen ravaging the apartment of the missing scientist Prof. Walter, before being caught (and presumably killed) by the authorities. When Richard the journalist wants to take pictures at the morgue for his newspaper, they are told there never was a monster. An investigation follows in which they learn the monster is the result of a scientific experiment gone wrong.