Wallas, a detective who arrives in a provincial city in northern France to investigate the latest in a series of political murders. He is large and in his forties, and he has shaved his mustache for this mission. His previous assignment had been the investigation of various theosophical societies. He had applied to the bureau for which he now works and had almost been refused because his forehead measures only forty-nine square centimeters instead of the fifty that the chief, Inspector Fabius, required. He has been given his first solo assignment and is to investigate the murder of Daniel Dupont. During his investigation, he frequently wonders what Fabius would have done, even going so far as to imagine himself to be Fabius. While trying to find a killer, Wallas also keeps trying to find a certain type of eraser he once saw, hence the title of the book.
Inspector Laurent, the man normally in charge of murder investigations in the city. He is not pleased with having his case usurped by an outsider, although he does his best to hide it. The most noticeable physical aspect of Laurent is that he is bald. Even though he does much less field investigation than does Wallas, Laurent figures out the truth of the matter by sheer reasoning ability, just as Inspector Fabius would have.
Daniel Dupont, a fifty-two-year-old, internationally respected university...
(The entire section is 529 words.)