In the past, reviewers were uncertain how to categorize Elmore Leonard’s non-Westerns. Did they belong in the mystery category, under thrillers, in street fiction or even lit noir? Book people finally settled for crime fiction.

Let’s just say that Leonard’s works constitute a genre all by themselves.

If imitation is indeed the sincerest form of flattery, the Birmingham, Mich., resident must be the most flattered author alive. Because he makes it look easy. Like a Harlequin romance, it’s formulaic: Come up with louche characters who operate in a milieu in which the average reader would be ill at ease; make sure there is oppositional action — frequently maiming or lethal (but not enough to detract from Leonard’s vaunted mastery of tough-guy argot); enter the required number of “F” words (in a variety of cases and tenses and modifiers) and rude references to body parts.

Then fill the spaces between with cleverly confusing dialogue.

If that’s the sort of book you like, “Road Dogs” (Morrow, $27) is for you. Leonard gets mileage from characters from three of his previous books: Jack Foley (“Out of Sight”), a guy with bank-robbing in his DNA; Cundo Rey (“LaBrava”), a Cuban so rich that he hires other characters as if they were disposables, and Dawn Navarro (“Riding the Rap”), Rey’s common-law wife, a pseudo psychic with scams galore and a lot more up her skirt.

Foley, whose fabled bank-robbing luck seems to have run out, is serving a 30-year sentence. In prison, he meets up with Rey, who kills problems (actual or potential) rather than letting them hang around. Rey takes such a likin’ to Foley that he springs for a classy lawyer (female, natch) and before you can say Willie Sutton, Foley is free as a bird — except that Rey is due to be released in two more weeks, and there’s no such thing as a free lunch where Rey is concerned.

What does Rey want from Foley?

And what does Navarro have in mind? Well, sex, for one thing. And money. But then that’s what most of the characters have in mind. What else is new?

Leonard has been cited for his ability to portray secondary or tertiary characters in pithily descriptive phrases. Most here are throwaways that whiz by as if included merely to uphold Leonard’s reputation for such artistry. As when Rey mentions a guy he knew who married a stripper, “the only one I ever saw wore glasses when she danced, so she don’t fall off the (expletive) stage.”

And so it goes for 262 pages.