This Poison Will Remain by Fred Vargas

A French archaeologist and historian, Fred Vargas (real name, Frédérique Audoin-Rouzeau) bends the police procedural to accommodate her own style and obsessions, which here include zoology, philosophy, classic French literature, and medieval history. Her Paris-based detective, Jean-Baptiste Adamsberg, grew up in the Pyrenees and has retained a certain mystical intuitiveness from his barefoot childhood in the mountains. Newly returned from a vacation in Iceland, he seems untethered as the book begins: “More vague and elusive than ever, with his wandering gaze and absent-minded smile, the commissaire seemed to have lost touch with the precisely carpentered joists which had always, in spite of everything, underpinned his approach.”

But as Adamsberg himself points out, “I can see perfectly well in a fog,” and proves his sharpness by neatly solving two crimes as a sort of a prelude to the main event, a situation in Nîmes involving the deaths of three old men who appear to have been bitten by brown recluse spiders. He thinks they may have been murdered, which his team finds ridiculous, but he persists, and soon finds himself entangled in an intricate web (I couldn’t resist) involving unspeakable acts of cruelty at an orphanage and a bona fide human recluse straight out of the Middle Ages.