Who's running around Manhattan lopping off heads with a bronze are and obsidian knife just like an ancient Toltec priest? That's the nut that homicide dick Stanislaus Rolk has to crack in this derivative but swiftly enjoyable police chiller by steadfast thriller-hand Heffernan (The Corsican, Acts of Contrition, etc.). The first killing--graphically described, of a middle-class woman--takes place outside the Metropolitan Museum of Art after a lecture/exhibit on the human, sacrificial religion of the Toltecs. Rolk is in attendance because he's the media-anointed "scholar of death," interested in all things murderous; he figures that someone at the lecture was the killer, and soon narrows his list of prime suspects to four, all connected with the exhibit's co-sponsor--the American Museum of Natural History. They include sexy lecturer Kate Silverman; her envious lesbian boss Grace Mallory; ambitious misogynist colleague Malcolm Sousi; and Fr. Joseph LoPato, the dipsomaniacal anthropologist/priest who's helped organize the exhibit. When Kate receives votive offerings fingering her as the killer's ultimate victim, Rolk takes her under his wing and beds her--a breach of cop-routine that jeopardizes his career nearly as seriously as the pressure on him from City Hall to find the killer fast, or from the Archdiocese to tread softly around Fr. LoPato. Further killings ensue, with great heapings of forensic, psychological, and anthropological detail (including a colorful sidetrip to Mexico and some inspired use of the gothic Museum of Natural History). Rolk, a bulldog of a cop, focuses on first one suspect, then another, until they themselves begin to lose their heads--all leading to a shocking denouement that's seeded fairly but will leave most readers scowling. Lightweight, but Heffernan paces like a consummate pro and ends with a big punch. This would--and probably will--make a terrific TV Movie of the Week.