FICTION : RAINBOW DRIVE by Roderick Thorp (Summit: $18.95; 394 pp.).

Even in Hollywood where life is cheap, and sometimes less than that, there’s something odd about this multiple murder. Not simply because it’s so awkward for Mike Gallagher, acting head of homicide, Hollywood Division--it is, after all, sticky to have all hell breaking loose like that almost across the street where he, in defiance of police policy, is shacked up with a beautiful German film director. It’s odd because a police helicopter is on the scene faster than is decent, or even possible, since no call has yet been put in. Odder, and something more than that, when in short order, Gallagher’s partner dies as his car plunges 400 feet down a canyon wall, and as subtle and not so subtle pressures are put on the detective by the top brass to forget both the five lives snuffed out on Rainbow Drive and the fact that he ever had a partner. Let’s welcome back to the police crime field novelist Roderick Thorp who, while he didn’t invent the genre with his near-classic study of the dark side of human nature, “The Detective,” at least laid the ground rules for how it should be done. Major or minor, no character Thorp creates is anything but three-dimensional and as this engrossing tale of Gallagher’s lonely investigation of the unholy alliance between police, the drug traffic and Los Angeles’ political power structure unfolds, the really sinister reason behind his partner’s death is gradually stripped away. And, clearly, Gallagher is next on someone’s hit list. Novelist Thorp is not for the lazy, easy diverted reader. Characters are thrown at you like handfuls of buckshot; incident explodes on incident. You don’t dare (even if you could) let your guard down for a minute. Each character and incident is there for a reason. Turn your back on this master of suspense and characterization at your own peril.