Kostman, a licensed Big Apple locksmith, certainly gets around the city in the pursuit of his profession. In his debut as an author (no license required), he offers a view of a few of the people and sights glimpsed beyond the doors he unlocks. This slender volume is a compilation of the odd scenes Kostman has run into over the years and the peculiar dialogues in which he was a bemused participant. The slices of life are as abundant and fragrant as a Broadway deli's pastrami on rye. As he changes tumblers or replaces lost keys, the intrepid journeyman encounters human interest with a vengeance, from 11-year-old Gloria, who looks after her apparently senile Papi, to the aging Mrs. Herzog, who believes her sister is robbing her blind. Kostman releases those locked in and lets in those locked out (never, it seems, feeling the need to verify the customer's right of passage). Bedeviled by jammed doors are doctors and gypsies, musicians and welfare clients, a psychiatrist and an East Side matron who could use one, a clandestine fireworks dealer and a troupe of naked old men. All converse freely and at length with the compliant locksmith/scribe. They may live in the precincts of poverty or in areas of affluence- -with no relationship to willingness to pay the locksmith's fee-- but most of the little dramas seem to happen in dark or dank places. ``The fish and piss odors produce an overpowering stench'' in one locale. ``At the bottom,'' in another, ``the alley is dark and everything is covered with bird shit.'' These are New York kinds of tales. Short stories by a locksmith with the key to a little Pandora's box of urban yarns. Written in the present tense with a touch of tense presence, the vignettes, while not earthshaking, provide salty, easy, lively city kibitzing.