This down-and-dirty L.A. mystery starts out as a hip, likable, subtly comic variation on the hard-boiled genre. . . but winds up as just another convoluted, sordid, implausible conspiracy tangle. The shamus is Terry Traven, a sometime counterculture hero (a Sixties leftover) who dresses like Philip Marlowe and specializes in runaways. Traven's case: born-again tycoon Athol Busby hires him to find missing son Lothar--a no-good who's been hanging around with punk-rock bands and drug dealers. So Traven's sleuthing almost immediately leads him to dead bodies, cocaine stashes, and to a guerrilla church (whose leader will eventually, falsely, be nabbed for the many killings). And Lothar, though first held for ransom after a kidnapping, turns up among the dead; his kidnappers seem to have crossed paths, fatally, with a gang of L.A. house-robbers. Further complications, too: homosexual secrets (de rigueur these days) and some sort of religious-fanatic, racist conspiracy. Too bad the plot's such a drawn-out mess--because Miller's semi-comic fix on the punk-drug subculture is often on-target, and the narration is fine and dry before it bogs down badly. A mixed debut, then--promising better things ahead once Miller settles down and decides whether to play things straight or tongue-in-cheek.