In “The Closers,” Michael Connelly’s complex, honorable, and intelligent detective Harry Bosch was assigned to the cold case squad, called the Open-Unsolved Unit in Los Angeles. His partner back then was Kiz Rider, for whom he had deep affection and respect, though no romantic involvement since she waltzed to a different tune. She’s back in the new book, “Echo Park” (Little, Brown, 416 pages, $26.99), though in a slightly diminished role as another outstanding female character has resurfaced on center stage.

If you’ve read the earlier Bosch novels (and if you haven’t, why not, for heaven’s sake?), you’ll remember Rachel Walling, now a member of the Tactical Intelligence unit, a group of hunters and gatherers created to identify terrorists, but that mainly discovers information for the DEA. Harry wants to get her help, but finds it a little uncomfortable at first.

When he first meets up with her after some years have passed,”It was an awkward moment. He didn’t know whether to hug her or kiss her or just shake hands. There was that night in Vegas, but it had been followed by that day in L.A., on the back deck of his house, when everything had come apart and things had ended before they really started.”

As one would expect, if a cop has the job of re-examining cases that have remained unsolved for years, he will gravitate to the particularly horrific ones, those that linger in the memory and grow brighter in the mind in the darkest hours of the night.

This much is profoundly true in this outstanding new novel, as Bosch is haunted by the fact that he and his partner missed a clue in 1993 that might have helped catch the villain who then went on to commit nine more brutal murders.

Just as in George Pelecano’s superb “The Night Gardener,” the self-inflicted guilt and frustration with which good cops must cope when they fail to catch murderers permeates Bosch’s story and gives it a richness that few narratives can match. The reader becomes enmeshed in the hell that bludgeons the detective as he struggles with the past as well as the present.

It is a tribute to Mr. Connelly that he is able to take so many familiar (familiar being a way of saying trite) plot elements and give them such vitality and freshness that they feel like they’re being encountered for the first time. A clever serial killer who uses a pseudonym that is a clue to his identity; an event from the past resonating in the present; a heroic police officer who flaunts the rules, engendering enmity in his superiors; a partner so close and so smart that they appear to have a psychic connection, and political infighting within the department that seems more important to the ambitious cops than solving crimes. We’ve seen them all before and surely will again, but no one uses the staples of the genre as well as this author who has already cemented his position in the pantheon of the greatest mystery writers of all time.

“Echo Park” begins when, by sheer happenstance, the police stop a van at 2:00 a.m. and discover two trash bags filled with women’s body parts. The arrest clearly suggests a solid case. As Mr. Connelly states, “Nothing like being caught in the possession of body parts. A defense attorney’s nightmare; a prosecutor’s dream.”When the D.A. decides to go for the death penalty, the killer agrees to confess to nine additional murders in exchange for a life sentence.

One of the murders to which he cops is of Marie Gesto, the case that has caused Bosch to grieve for so many years. She was a young woman who simply disappeared one day, her body never found. Bosch cannot erase the snapshot of her neatly folded clothes from his brain. He wants the captured man to be the murderer, but he doesn’t believe him. There are inconsistencies and, rather than just accept the confession, as his bosses want him to do, Bosch feels compelled to poke around, much to the irritation of one and all.

The brass doesn’t really care if the confession is true; they just want to close the case. If it means ignoring evidence, or even making some up, that’s fine by them. “To Bosch,” Mr. Connelly writes, “it seemed that as far back as you could remember in L.A., the fix was always in.”

The City of Angels has been a fertile field for crime fiction for a long time. Raymond Chandler flourished there, and so did Nathaniel West, Horace McCoy, many of the top pulp writers, and among today’s giants of the genre, Robert Crais, James Ellroy, Andrew Klavan, and Joseph Wambaugh. Perhaps that should not be a surprise. As Mr. Connelly writes, “L.A. is a sunny place for shady people.”

“Echo Park” is a hard-boiled cop novel, but a poignant one, examining with clarity and insight two equally powerful drives: the internal struggle of a good man as well as the external challenge of solving a mystery with finality, etching the solution in marble, so that it’s able to withstand the magnified examinations of time.

As with his masterpiece last year, “The Lincoln Lawyer,” Mr. Connelly has again produced that rarity in mystery fiction, indeed a rarity among all fiction: a flawless work of art that perfectly balances action and suspense with intelligent dialogue and fleshed-out characters.

What may not be surprising (since he was a police reporter) is that Mr. Connelly understands the mentality of police officers. What is surprising is how well he seems to understand the mentality of women. But what’s shocking, and a little scary, is how well he seems to understand the minds of vicious killers.

Mr. Penzler is the proprietor of the Mysterious Bookshop in Manhattan and the series editor of the annual “Best American Mystery Stories.” He can be reached at ottopenzler@mysteriousbookshop.com