It has become increasingly clear that U.S.-born, Dublin-based Tana French is the most interesting, most important crime novelist to emerge in the past 10 years. Now, with the publication of her sixth novel, “The Trespasser,” it’s time to recognize that French’s work renders absurd the lingering distinction between genre and literary fiction — the notion that although crime novels might be better plotted and more readable, only literary fiction, supposedly blessed with superior writing, characterizations and intellectual firepower, deserves the respect of serious readers.

"The Trespasser," by Tana French (Viking)

French pointedly rejects that dichotomy. “I’ve never been much for the artificial divide between ‘literary’ fiction and ‘genre’ fiction,” she said in a recent interview. “I’ve never seen why audiences should be expected to be satisfied with either gripping plots or good writing. Why shouldn’t they be offered both at once?” All she is asking, for herself and other of the best crime writers, is that they not be denied critical recognition simply because they write about murders. For God’s sake, “Hamlet” is about a murder.

French’s new novel brings back the two young detectives from the Dublin Murder Squad, Antoinette Conway and Stephen Moran, who solved the prep-school slaying in her 2014 offering, “The Secret Place.” Conway narrates “The Trespasser,” and with her anger, intelligence and toughness emerges as French’s finest character yet. (Or would that still be Frank Mackey from “Faithful Place”? Hard to say.)

Conway and Moran are assigned to investigate the murder of a young woman found dead in her Dublin home. Her boyfriend is the initial suspect, which leaves the two less than thrilled to have the case, because it looks like a routine domestic killing and solving those carries no glory. Because the case against the boyfriend is circumstantial, Conway and Moran shift their attention to another suspect, only to have more senior detectives pressure them to arrest the boyfriend. The partners begin to fear that their colleagues have some agenda other than the truth.

Conway, the lone woman on the Murder Squad, has for months been a target for abuse. Her colleagues make ugly comments about her looks and presumed sex life; they steal documents from her desk; once she discovers that someone has spit in her coffee. She stubbornly refuses to bow to the sexism, because she loves being a detective. “When it’s right, this job is the hit that speed freaks throw their lives away hunting,” she says. Still, the hazing is tough, and she’s starting to wonder if she should quit.

Tana French (Kathrin Baumbach)

As the investigation continues, French increasingly focuses on the Murder Squad itself, on the kind of men the detectives are and how they do their jobs. Many fine writers have written well about police work — Michael Connelly and the late, great Ed McBain leap to mind — but I don’t recall any novel that digs more deeply into police culture, the tricks of the trade, the ugly side and the heroics, too, than French does here.

My only reservation about “The Trespasser” came when French had one character carry out a highly elaborate and dangerous scheme to inflict revenge on another. I felt much the same when French, in “The Likeness,” had a female detective impersonate a murdered woman who had been her virtual twin. I thought both events unlikely — but not impossible — and ultimately the skill and conviction of French’s narrative won me over.

Starting in 2007 with “In the Woods,” which won an Edgar Award and a slew of other prizes, all of French’s novels have been international bestsellers. The books have achieved this success because they’re unfailingly intelligent and beautifully written, and because they are never lurid — there’s little sex or gratuitous gore in them. Their magic lies less in the crimes themselves than in the distinct new worlds French creates to showcase each of them. Readers understand and embrace her work; it’s time for more of the people who review books and award prizes to rethink the cliches about genres and recognize the excellence — the literary excellence — of her work.

Patrick Anderson regularly reviews mysteries and thrillers for The Washington Post.

THE TRESPASSER

By Tana French

Viking. 449 pp. $27