The crimes of a quasi-religious psycho criss-cross with those of sadistic drug-dealers--in another atmospheric, grimly vivid, somewhat overwrought investigation for Brooklyn cop Francis DeSales (Only the Dead Know Brooklyn). Who is the man in the black hat and long black coat, seen walking away with a little Brooklyn boy. . .just hours before the child is found murdered? Some people in the neighborhood are sure that the ritualistic killer is a Hassidic Jew; the murder seems to be connected to tensions between Jewish sects in area. But when the voodoo-style killing of a black man (his fingertips surgically removed) soon follows at the Botanic Gardens, lean, mean DeSales--in surly collaboration with rather wimpy Prof. Tim Desmond--gets quite skeptical about all these religious trappings. And the reader already knows that, while there is a psycho (with Amish obsessions!) on the loose, most of the mayhem is the work of a drug-baron intent on keeping DeSales distracted and confused. Things become increasingly melodramatic and contrived in the book's second half: DeSales' new bedmate Megan, a feisty TV newswoman, is kidnapped by the bad guys; in the stagy climax, the psycho grabs Desmond's little son. . .just as, coincidentally, DeSales traps the drug-dealer a few yards away. But, with a slew of flavorsome character-vignettes (the villain's spacey moll, the preening Botanic Gardens curator) and lots of raunchy, streetwise dialogue, this is darkly textured entertainment for connoisseurs of intense, faintly baroque police-procedurals.