More than a decade after her debut novel, “The Last Samurai,” impressed critics and readers alike, Helen DeWitt has returned with “Lightning Rods,” a funny, filthy volume that starts out innocently enough. Joe is a hapless hero, a failed salesman of encyclopedias and vacuum cleaners, who “had once sold a single Electrolux and eaten 126 pieces of homemade pie in a time frame where most salesmen would hope to reverse the ratio of vacuum cleaners to pie.” He spends his days entertaining himself in his rented trailer; he reads magazines, watches videos, and fantasizes about women and — wait for it — walls.

By the third page of the novel, no matter how innocent we thought lonely, sad-sack Joe to be, we are swiftly and utterly disabused. “The woman would have the upper part of her body on one side of the wall. The lower part of her body would be on the other side of the wall”: Joe channels any creative energy he has into his increasingly eccentric fantasies, which are imagined in such scrupulous detail there is little fit to print here. At a low point, while contemplating sex and scarcity and the numerous industries that have flourished as a result, Joe, current resident of Eureka, Fla., and former resident of Eureka, Mo., has his eureka moment. He will solve the problem of sexual harassment in the workplace by starting a temp agency that offers the services of “lightning rods”: women who provide sex on-site and therefore absorb all the destructive liability of male desire.

Recreating the apparatus of his fantasies, Joe has the lightning rods liaise with clients through a wall that divides the men’s restroom from the ladies’, which keeps the sex as anonymous as can be. As he quickly finds out, however, ensuring the smooth operation of such facilities requires investments in employee support (“an in-house online network . . . in which to air their views”), equipment (a handy magazine rack) and attire (PVC leggings, so that the lightning rods’ anonymity cannot be compromised by skin tone and Joe can proudly declare himself an “Equal Opportunities Employer”). He bumbles toward profitability, thanks largely to his two most punctilious employees. Lucille will use the money she earns as a lightning rod to enroll in law school and become a million-dollar-a-year litigation lawyer; Renée, who makes the most of her active time on the job by reading Proust in the original French (“Instead of cluttering up her mind with bad feelings, she had actually improved her mind”), will also enroll in law school and become a Supreme Court justice. Both women are depicted as unflappable pros, each one “the woman in a thousand” who sees her duties as “no different from holding hands.” Lucille, whose business philosophy seems equal parts McKinsey and Nietzsche, views any unpleasantness on the job as something that will make her stronger: “No matter what happens, nothing is going to drag you down.”

“Lightning Rods” may be rived with clichés, but they are clichés of a very deliberate kind. “Women,” Joe thinks, “were being molested in the workplace solely because their colleagues did not have a legitimate outlet for urges they could not control.” What at first glance might look to be a reasonable hypothesis, couched in the familiar, pseudoscientific terms of cause and effect, is in fact something else entirely. Notice how much lazy presumption is tucked into the sentence: “solely because,” “legitimate outlet” and “urges they could not control.” The language is perched on the line between banality and monstrosity. Joe, trying to satisfy a client’s request, realizes “the thing that separates the sheep from the goats is the willingness to go that extra mile.” His brisk pep talks only highlight the depravity of the market he is creating, which will owe its success to the orderly march of efficiency, the sensible pursuit of supply and demand.

DeWitt points to problems that are recognizable and real — how men’s desires can differ from women’s, how harassment can upend a workplace — and offers up a modest proposal using the familiar rhetoric of our time. An author could easily succumb to the timidity of good intentions, too fearful to include anything that might allow a reader to ask questions and, oh dear, nurture doubts about the author’s ultimate decency. DeWitt, however, is willing to take her satire as far as it will go, giving us the freedom to read it (or even misread it) as we choose. The lightning rods have a positive effect: absenteeism goes down, productivity goes up. A frequent user of the facilities, having been brought to “a new level of self-awareness which he had not had before,” sees his love life improve. Lucille and Renée are furthered by their jobs rather than destroyed by them.

To find fault in DeWitt’s broad strokes, in the novel’s brusque disregard for any depth of feeling, would be like denouncing Mel Brooks for having made “The Producers” instead of “The Pawnbroker.” DeWitt has shown herself perfectly comfortable already with the big novel of both feeling and ideas; “The Last Samurai” was laced with interludes of Icelandic saga, ancient Greek, family dysfunction and a child’s desperate search for a father. “Your Name Here,” an intermediary work that was excerpted in the journal n+1, read like a sprawling commonplace book for the fractured digital era, filled with e-mails, exclamations and digressive riffs. With “Lightning Rods,” she has taken on an entirely new set of concerns and constraints. This novel is less nuanced, more distilled; the strange, obsessive language that runs through her other work has largely been replaced by the can-do platitudes of sales force training and motivational seminars. Yet in taking on a premise that might look like a bit of wish-fulfillment if deployed by a male writer of similarly satiric gifts (Men Have Anonymous Sex on Demand, Everybody Wins!), she confidently deploys this bland vocabulary to serve her own idiosyncratic ends.

I suspect DeWitt would be horrified by anything as trite as “the moral of the story . . . ,” but “Lightning Rods,” read literarily rather than literally, does make gestures toward exposing a larger affliction, something that resides just as much in obnoxious language as in the obnoxious workplace it describes. Several characters resort to a grimly determined “let’s face it” before offering some unpalatable observation they proceed to accept as unshakable truth. Joe, for his part, bucks himself up with the verbal equivalent of a resigned sigh: “Any salesman knows that you have to deal with people the way they are. Not how you’d like them to be.” DeWitt, whose interest in languages was apparent in “The Last Samurai,” has adopted here the idiom of America’s pragmatic temper, and the story of Joe and his business plan shows how a fetish for common sense can make for silly, sleazy extremes. The basic premise for “Lightning Rods” is so audacious that it might be hard to get past its general conceit, but its true brilliance lies in DeWitt’s careful deployment of language so common that we no longer see it. As any million-dollar litigation lawyer or two-cent literary critic will tell you, the devil is in the details.