Unmistakably authentic detail in action and atmosphere distinguish a thriller by and about Dallas policemen cracking car theft and drug rings in one very nasty week. ``Terry Marlow'' is (or are) a Dallas police sergeant and a former Dallas SWAT captain. Not for the fainthearted, this slice of the lowlife begins with a bloody drug-dealer shootout and gets more and more violent, even though the lead cop, Sgt. Bill Clark, heads up the city's auto-theft squad rather than one of the rougher operations. Clark's troops, who normally spend their time closing down chop shops, have opened the smelly trunks of a couple of cars to find butchered bodies of nude go-go dancers. The young victims have had the bad luck to run afoul of ``Mack,'' a sadistic biker who has formed a drug-and-gun-dealing partnership with an apparently respectable and rich young businessman. That drug business is of great interest to an up-and-coming Mexican-American gang and to a Jamaican posse. Complicating everybody's investigations are two undercover policewomen, one of whom has been hooked on speed by the unspeakable Mack. The other officer has donned scanty vest and skirt to work as a waitress in a nude-dancing dive, where she meets the lonesome Sgt. Clark in the middle of a mugging. The interrelationships of the investigations being carried out by a dozen different divisions of the police come to light in an unauthorized meeting of politically incorrect but very clever officers. Brutal, nasty, and quite good. Believable heroics and a breakneck pace.