Let’s raise a flute of Veuve Clicquot to French polymaths. In the mystery field alone, we have Fred Vargas (the pen name of Frédérique Audoin-Rouzeau) who is both a novelist and an archaeologist; and Michel Bussi, a fiction writer who also is a professor of geopolitics.

I can’t speak to either writer’s academic industriousness, but I can say with assurance that Madame Vargas and Monsieur Bussi are prolific writers for the public at large, she keeping two detective series stocked with new titles, he turning out one stand-alone bestseller after another. Bussi’s latest is the gripping “The Double Mother,” which may set a record for number of plot twists between two covers.

The basic story line is simple enough. Malone Moulin, a 3-year-old resident of Le Havre, France, insists on two things: toting a ratlike stuffed animal with him wherever he goes, and asserting that his parents are impostors. All the other adults in Malone’s life except one scoff at his disavowal of his parents, whom Malone likes well enough and generally obeys even while applying suffixes to their role-names: instead of simply Maman, she is Maman-da; and he is Papa-di. The only grown-up inclined to side with the boy is Vasily Dragonman, a child psychologist who believes Malone may be telling the truth — or at least that he is not delusional — because of how firmly he sticks to his guns and to his stuffed animal, Gouti.

Early on, Malone himself furnishes a key to the puzzle while playing outside of his school, in which he can see his so-called parents conferring with the headmistress. “Behind the windowpane,” he reflects, “they must be talking about him. And about his Maman, perhaps. Not Maman-da, but his Maman from before. Maybe about pirates too, and rockets and ogres. The adults knew all about that. He could only remember because of Gouti.”

Dragonman fills us in on the state of a 3-year-old’s memory bank. Typically, it doesn’t keep things on deposit long. As adults, few of us can remember much of anything from that stage of our lives, and a 3-year-old would be unable to recall events from his short past unless they were getting steady reinforcement from an outside source, a role that Gouti might be capable of playing. How the toy-to-boy communication takes place, however, remains unclear for quite a while because Malone refuses to part with his aide-mémoire.

Dragonman is concerned enough to report the matter to the police, who initially give it a low priority because so little appears to be at stake. In charge of the case is a female captain, Marianne Augresse. Single and with her biological clock ticking away, Marianne notes the irony of her romantic predicament. “It was the most liberated, most demanding women, those least inclined to throw away their youth on the first idiot they encountered, who — as their forties approached — would find themselves having to go out hunting for a man.” In an amusing departure from the norm, we are privy to this professional woman’s sexually objectifying thoughts about her subordinates, among them the new intern, who is almost 20 years her junior. “[He] really knew his stuff,” Marianne concludes about the intern’s research on the first case assigned to him. “She’d like to see if he was just as talented away from the office.”

Bussi is one of those thriller writers who heighten suspense by shifting from one character’s viewpoint to another with calculated aplomb. Fortunately, he draws his characters so well that we don’t mind being wrenched away from Malone in crisis, say, to Marianne in consternation. The author himself comments archly on all this back-and-forth when he has Marianne complain about the burden of managing more than one case at a time. “It was a bit like reading a thriller with two parallel stories, with the switches between the two threads speeding up as the book progressed. . . .” A few pages farther along in this thriller, the threads of Marianne’s two most compelling cases oblige by weaving themselves together.

To change metaphors, other slabs of disparate material will soon be fitted into place, especially in the novel’s final hundred pages, and what a pleasure it is to be a construction-site rubbernecker. A long book that goes quickly, “The Double Mother,” zestily translated by Sam Taylor, is likely to stay in your mind for years to come, even if you don’t have a stuffed animal to coach you.

Dennis Drabelle is a former mysteries editor of Book World.

The Double Mother

By Michel Bussi

World Noir. 480 pp. Paperback, $17.99

Translated from the French by Sam Taylor