During his 10-year writing career, Robert Deane Pharr has become obsessed with the nightmare world of prostitution and narcotics in his adopted home, "a tiny nation called Harlem," and he writes about it with the assurance of one who has put in his time on the bottom. His fourth book is a violent caper novel seemingly written with one eye on the black-movie-rights market. And this story of an uptown heroin war, in which a tattered band of adventurers film-flam the big heroin lords with a phony "heroin still" supposedly capable of quintupling the street value of drugs, would indeed translate well to the screen. But no movie could capture the haunted, painful narrative voice which has always been Pharr's chief strength.

At times, Giveadamn Brown reads like the ravings of an angry drunk in a bar; at others, it approaches the tight-lipped grace of Dashiell Hammett's Red Harvest or Robert Stone's Dog Soldiers. The new novel is short on the sensitive characterization which distinguished Pharr's first two novels, The Book of Numbers and S.R.O. But there is plenty of action, including a slambang finish pitting some spectacularly cinematic villains (and the corrupt forces of the N.Y.P.D.) against a flatbed full of dynamite. And, as always, Pharr includes his own knowing, surealistically honest vision of life in Harlem. (My favorite scene is one in which teenage drug pushers shoot baskets on a playground for hundred-dollar bills, while their uniformed chauffeurs idle their Continentals in the street.) The mixed result is an intermittently compelling, oddly believable fever-dream of sex, money, and death. (Doubleday, $7.95)