“The Seventh Function of Language” by Laurent Binet; Farrar, Straus and Giroux (368 pages, $27)

Walking home on Feb. 25, 1980 after lunching with future French president François Mitterand, Roland Barthes — one of the great French intellectuals of the last century — was struck by a laundry van, sustaining serious injuries. By late March he was dead.

Barthes’ end has gone down as an accident. But what if he was actually murdered? That’s the question Laurent Binet asks in “The Seventh Function of Language,” a witty and playful novel true to the inquiring spirit of a critic who’d continually made clear that nothing we see is ever quite what it seems.

What ensues is a shaggy dog detective story involving a document Binet imagines Barthes writing when he died: the key to the seventh function of language, a never fully developed supplement to the six functions through which linguist Roman Jakobson attempted to explain how communication works.

“Let us imagine a function of language that enables someone … to convince anyone else to do anything at all in any situation … Whoever had the knowledge and mastery of such a function would be virtually the master of the world.”

So posits Umberto Eco — yes, that Umberto Eco, in a novel strongly reminiscent of “The Name of the Rose,” published in that same year of 1980 in which Barthes died. Eco explains how such a magic spell might work to Jacques Bayard and Simon Herzog: a grumpy right-wing French detective and the lusty left-wing academic drafted as his sidekick.

Eco’s description makes clear why such a document would be valuable; in Binet’s novel, the murder suspects hoping to get their hands on it include Communist spies, French politicians and many of the leading lights among the French intelligentsia, all of them concerned with the relation between language and power.

That means considerable airtime here for writers like Michel Foucault and Jacques Derrida, Julia Kristeva and Philippe Sollers, Louis Althusser and Gilles Deleuze. Binet makes them characters and inserts Easter eggs galore drawn from their writings.

Hearing this crowd natter won’t be everyone’s cup of tea; self-important intellectuals will strike some readers as more boring than brainy.

It pays to remember that when the literary theory craze was at its height some 30 years ago, luminaries like these were celebrities; I’ll admit that encountering them again here made me nostalgic for a time when reading their seductive prose rocked my world.

And with good reason: While they can be maddeningly difficult and obscure, their body of work offers powerful tools for decoding the world, from the novels we devour to the menus we scour. Think of them as first-class detectives adept at reading signs, which is why Bayard and Simon — an old-fashioned gumshoe and a new-fangled linguist — make a good pair.

As they track their suspects from Paris to Italy and then to Cornell, they’ll dodge Bulgarian agents’ poisoned umbrellas; spend time in a secret debate club addressing topics like the written vs. the spoken word or soccer and the class struggle; sleep with randy academics and left-wing revolutionaries; and battle the Mafia.

Along the way, Simon will gradually come to suspect that he might be a character in a novel, trapped in a master narrative and subject to another’s whims. Here “Seventh Function” recalls “HHhH,” the brilliant debut novel in which Binet explored another such narrative: the Nazi fantasy of world domination.

There as here, Binet joins the French intellectuals he clearly admires in refusing to believe that such narratives are ever truly closed and self-contained.

Like the intrepid few who rise against the Nazis in “HHhH,” Simon holds to the belief that “it is never too late to try to change the course of the story.” Bullies can dream all they want of using language to control what we say. But as every good novelist knows, there’s more than one way to tell a tale. Once again, Binet’s telling is flat-out ingenious.