Those of us who read a lot of mystery fiction, not to mention people who watch cop shows on television and enjoy crime movies, have become very used to the notion of the odd pairing of partners, be they official members of a police force or private investigators.

In what passes for creativity, writers have matched disparate demographic types to the point that there is virtually no odd couple, no matter how far-fetched, one could imagine that hasn’t been tried.

Most commonly, it’s a white cop and a black cop, and not far behind is a male and a female, followed by mix-and-match races and genders. Equally trite is the tough cop teamed with the compassionate one, the dinosaur with the modern thinker, the romantic with the cynic, the grizzled veteran with the callow rookie and – everybody’s favorite – the by-the-book Boy Scout with the renegade who’s constantly in trouble for breaking “every rule in the book” but who gets the job done.

Most of these are as utterly and obviously contrived as a Rube Goldberg mechanism, so predictable that the experienced reader or viewer can practically quote the dialogue before it’s spoken.

It is the abundance of these cliched couples that makes Andrew Klavan’s mismatched private investigators, Scott Weiss and Paul Bishop, such a rich reading experience. Fully realized, these fascinating tough guys have their strengths and, oh boy, do they ever have their failings. They made their debut in “Dynamite Road” and are, happily, up to their eyeballs in some really bad stuff again in “Shotgun Alley” (Forge, $24.95, 301 pages).

Although Mr. Klavan has won the Edgar Allan Poe Award, made the bestseller list with “Don’t Say a Word” and “True Crime” (both of which were filmed, the first with Michael Douglas and the second with Clint Eastwood), and been described by Stephen King as “the most original American novelist of crime and suspense since Cornell Woolrich,” he has not yet become a household name. Perhaps time will correct this injustice.

Weiss is a former cop who carries agony everywhere he goes. “Sometimes,” Mr. Klavan writes about him, “it felt like life was all salt, and he was just one big wound.” He seems always sad, but he’s not. His gentleness, his compassionate understanding of the pain that people sometimes have to endure, his pitying eyes, give one the sense that he could never be happy. This great bear of a man is, as Mr. Klavan so eloquently portrays him, “a great soul locked out of life, a great soul pressed longingly against the window of the world.”

Weiss displays all “that curdled romanticism, all that gentleness battle scarred by the street and his marriage and his cop’s existence” and serves relentlessly as the conscience of the detective agency – frequently to the irritation of his top gun.

When Weiss met up with him, Bishop was a biker thug, a criminal who enjoyed violence and lawlessness. While still a cop, before starting his own agency, Weiss Investigations, he caught up with Bishop and gave him a savage beating instead of arresting him. Bishop had just come back from an important job in military service where he flew helicopters, got a lot of medals, and killed people face-to-face.

It was evident that the terror and the slaughter had got to him, that he had become a lost soul, that “his interior world was practically a vacation spot for personal demons.” Weiss wanted to give him another chance, asked him if he wanted to be a piece of [garbage] his whole life. A year later Bishop asked him for a job.

In “Shotgun Alley” a man planning to run for political office asks the agency to do a job. His sexy, young daughter has run off with a biker gang so tough that they have the unofficial name of Outriders, since its members have been disgorged from the Hell’s Angels and other gangs for being too wild.

Bishop, whose good looks and cool demeanor have provided unfailing success with women, is told by the girl’s father to seduce her in order to get her away from Cobra, the head of the gang, so that her activities won’t cost him the nomination. What wasn’t expected was that Bishop would fall for her, fall so hard that he is blinded to morality, potentially lethal danger, the legality of what he is doing, his job commitment – everything except his passion for her.

There are other people at the agency, including the lovely and impossibly sweet Sissy and the young man, recently out of college, who narrates some sections in first-person narrative. He read Hammett and Chandler and dreamed of being like one of their detectives, so naturally Weiss and Bishop are his heroes.

Although he is mainly inexperienced, shy, and inept, he charmingly assists in another case presented to the agency, of a feminist college professor who receives sexually harassing e-mail messages. These messages are so explicit (fair warning) that they inspire the fledgling private eye to say “Holy canoodle” and “wowser,” and Weiss to call his favorite escort service to fulfill previously unsuspected fantasies, over which he later anguishes.

I could have lived without two trivial lapses. The first is the sort of thing an editor should have caught. In the opening scene, Cobra whips out a bayonet and stabs a shopkeeper. On page 91, he is said to have been “shot where he stood.” Secondly, the beginning of a very sweet romance is described charmingly, but no second date ever occurs. Maybe it’s just me, but I’d have liked to see where it could have gone.

There really isn’t very much detection here, most of the pages being filling with harrowing adventures, as well as some hilarious (and frequently profound) philosophical musings. But this is no lapse. If “Shotgun Alley” had been any more compelling, I’d have needed more tranquilizers than Travis Bickle.

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 openzler@nysun.com.