By Fred Vargas

Translated from the French by Sian Reynolds

Penguin. 361 pp. Paperback, $15

“The Ghost Riders of Ordebec: A Commissaire Adamsberg Mystery” by Fred Vargas. (Penguin)

Halfway into the eighth Commissaire Adamsberg policier, Adrien Danglard, the deputy to the head of the Paris Serious Crimes Squad, tells his boss what he thinks of an unusually eccentric household of homicide suspects in a Norman village: “Could be a whole family of killers, self-contained, sheltered from the outside world. All of them with a screw loose, they’ve been badly abused, they’re wild, incredibly talented and very engaging.” Except for the sheltered and abused parts, Officer Danglard could have been describing his creator, Fred Vargas . Of course, Vargas, pen name for historian and folklorist Frederique Audoin-Rouzeau, has a screw loose only in the sense that her mysteries are darkly whimsical — magical realism with its feet on the ground in a highly entertaining French way.

Of the several cases that the diminutive, nonchalant, often self-absorbed Inspector Adamsberg must puzzle through in “The Ghost Riders of Ordebec,” he obtains a confession in one of them in the first seven pages. A crossword-puzzle freak admits to having become fed up with his wife’s fastidiousness and stuffed a baguette down her throat. How’s that for a French way to solve a domestic problem? A second case is unofficial and trickier: Adamsberg decides to track down the mean child who tied a pigeon’s feet together, leaving it in a park to starve. The commissaire is aided in this admirably quirky task by his son Zerk, a young man who has appeared in Adamsberg’s life only recently; the lad’s mother, a long-ago lover of the inspector, was too miffed at him to let him know he had a son.

Adamsberg receives some unexpected help in the pigeon case from a hapless young firebug named Momo, a suspect in the third urgent mystery he must solve, the death of an industrialist whose car has been set alight with him strapped inside it. Adamsberg suspects the tycoon’s sons are involved, and Vargas comes up with an extra-judicial maneuver meant to get at the truth that’s as startling as it is funny.

The commissaire’s fourth and primary case is the toughest for him to solve. An old lady from the Norman village of Ordebec persuades Adamsberg to get involved in a situation the local gendarmes have refused to take seriously. The old woman’s daughter, Lina Vendermot, claims to have witnessed the ghost riders from a thousand-year-old legend carrying on frightfully, screaming and throwing off smoke and flames, on a rural road. Many locals believe that the Furious Army shows up periodically to wreak vengeance on people who have been getting away with cruel habits. A hunter who takes pleasure in killing female woodland animals and their young is the ghost rider’s first victim, and young Lina says she knows who’s next. The local cops insist this is all superstitious hooey, so it’s the rational man from Paris who suddenly finds himself on the side of the susceptible bumpkins.

It’s hard to say who comes across as the most arrestingly peculiar here, the Vendermot family or the commissaire and his own squad. One of the Vendermot brothers speaks everything backwards — he pronounces “weird” as “driew” — and another thinks he’s made out of clay. Lina is “irradiated” with a potent erotic aura that makes it hard for Adamsberg to think straight when he’s around her.

Adamsberg is by his own description “a peasant, a mountain dweller and cloud shoveller” who relies on a kind of quivering intuition to point him in the direction of concrete evidence. Among the officers under his command, he tells a fellow commissaire, are “a hypersomniac who goes to sleep without warning, a zoologist whose specialty is fish, . . . a woman with bulimia who keeps disappearing in search of food,” and a second in command with a serious white-wine habit. The novel also includes a prison inmate osteopath who brings an 88-year-old witness back from the brink of death, and an unconscious cop who survives being run over by a speeding train when a colleague who is unable to lift him positions him instead neatly between the rails. Envious of the run-over gendarme, one of the Vendermot brothers exclaims, “Wow, that’s what I call an artistic experience.” He is not merely eccentric, he is quite winningly French.

Lipez writes the Don Strachey private eye novels under the name Richard Stevenson.