By Walter Mosley

Norton. 219 pp. $18.95

The black private detective is hardly a staple of American fiction. The only one to make an impression is Ernest Tidyman's John Shaft, and his fame probably owes more to the three Shaft films than to Tidyman's novels. Fictional cops, too, are not often black. Outside of Virgil Tibbs in John Ball's books (the best known of which, "In the Heat of the Night," was also made into a film and a television series) and Coffin Ed Johnson and Grave Digger Jones, the tough Harlem cops in Chester Himes's novels, "the Man" -- the police -- has been white.

It was only a question of time. Almost 20 years after Shaft hit the streets, a new black detective enters the field, though strictly speaking he (Easy Rawlins is the name) becomes a shamus only at the end of Walter Mosley's "Devil in a Blue Dress." Rawlins, however, is no Shaft. He's not hip, not cool; he isn't from Harlem or even of the same generation. Mosley sets his story in Los Angeles and in 1948, a time when not many blacks were native Californians. Easy himself hails from Houston and only settled in L.A. after the war.

"Devil in a Blue Dress" begins as a hard-boiled pastiche replete with either dull or jarring similes: hands "like {a} black catcher's mitt," a grip "like a snake coiling around my hand," cracks in marble that looked "like a web of blood vessels in a newborn baby's head." Then, abruptly, the similes come to a stop, and a more thoughtful, introspective narrative emerges. The story is Easy's, and he's in a fix. Just fired from his job at a defense plant, he's looking to make his mortgage payment. So when a big, tough-looking white man suggests that Easy help him locate one Daphne Monet, who likes to run with a black crowd, Easy reluctantly agrees.

Turns out that Daphne is the mistress of an L.A. power broker who wants her back; turns out she's run off with another man as well as with $30,000. This makes her attractive to the sort of galoot who'd rather fondle money than Monet. Although strong and resourceful, Easy is not a standard-issue tough guy. And when people he has talked to begin dying with sudden apertures in their bodies, he calls on an old childhood pal for help. But his friend is a sociopathic type himself, and before all the mayhem has ended, the reader isn't too sure who killed whom and why.

A good private-eye novel, however, is not really about violence; it's about the fallibility of people, about the grotesqueries of modern life, and not least it is about one man, the detective, who defines the moral order. In these respects, Mosley mostly succeeds. Plus he writes well. The scenes between Easy and his adversaries, both black and white, are nicely handled, and the dialogue's shifts in tone and temper, depending on which race Easy is dealing with, are worth remarking. And yet one cannot help being annoyed by the film of self-consciousness clinging to the narrative. Easy constantly explains himself to us instead of letting his reactions to people and events speak for him. And there is this little "voice" in his head that he (and we) listen to. It doesn't speak often, but once is already too much.

According to the book jacket, the next Easy Rawlins mystery is to be titled "A Red Death," which raises the prospect that a color motif (a` la John D. MacDonald's Travis McGee series) is going to play a role in Mosley's books. What's the point? Mosley should avoid gimmicks. He has found a rich vein to mine, and the tools he uses shouldn't distract us. Anyway, the similes, broads and hard-boiled patter have been done a thousand times before. It's information we want, the texture of ordinary life. How did blacks of that time and in that place live? What did they think about? What were their hopes? Although Mosley does not neglect these questions, he often subordinates them to pyrotechnics and twisty plot developments. It's not often that a reader wants less plot in a detective novel, and in a way it's a measure of Mosley's ability that, in this instance, that is precisely what at least one reader did want.

The reviewer is a writer and critic.