IF I HAD to supply a label for these novels, the first two volumes of Paul Auster's New York trilogy, it would be something like post-existentialist private eye. Though they are steeped in the stuff of the hard-boiled detective story, City of Glass and Ghosts evolve into studies in obsession and withhold the last-chapter solution obligatory in the unadulterated genre. It's as if Kafka had gotten hooked on the gumshoe game and penned his own ever-spiraling version.

Other comparisons might be drawn -- to Nabokov, to Dino Buzatti, to Witold Gombrowicz -- and presumably Auster would welcome them. His City of Glass protagonist, mystery-writer Daniel Quinn, "knew almost nothing about crime. He had never murdered anyone, had never stolen anything, and he did not know anyone who had. He had never been inside a police station, had never met a private detective, had never spoken to a criminal. Whatever he knew about these things, he had learned from books, films and newspapers. He did not, however, consider this to be a handicap. What interested him about the stories he wrote was not their relation to the world but their relation to other stories."

One night this bookish soul gets a call for a detective -- a wrong number. But so distraught is the caller and so empty Quinn's life that he decides to play along, pass himself off as the detective, take the case. (The "real" detective's name, by the way, is Paul Auster -- the author's -- and, Hitchcocklike, he appears in the story.)

This decision brings Quinn face-to-face with the caller, Peter Stillman, a spiritual kinsman to Victor, the wild boy of Aveyron, and Kaspar Hauser -- people who grew up in such solitude that they never wholly acquired the power of speech. Stillman's plight is a little different. At the age of 2, his wife explains, he was shut up in a room with covered windows and kept there for nine years by his fanatical father. The excuse for this cruelty was the father's crazed urge to recapture the primordial human language spoken by Adam and Eve. He believed that an innocent and isolated child would grow up speaking that very language.

The authorities finally caught on, and both father and son were institutionalized. Though the son has since emerged from therapy and married, he is still deeply disturbed. Sometimes he can't help screaming. He looks and talks like Andy Warhol in the throes of glossolalia. "Wimble click crumblechaw beloo," he demonstrates for Quinn. "Clack clack bedrack. Numb noise, flacklemuch, chewmanna. Ya ya ya. Excuse me. I am the only one who understands these words." Quinn's assignment is to tail the father, just released from the hospital and conceivably planning to reclaim his grip on Peter.

After this brilliant and original beginning, the story settles down to more standard nightmarish level. Quinn becomes obsessed with the father, whose life work has evolved into concocting names for things that no longer serve their functions -- for example, a broken umbrella. That Quinn will end up as a street person, destitute, feverishly filling out a red notebook, and depriving himself of sleep so as not to miss a single one of the father's movements becomes predictable, almost inevitable. For me the novel's electrifying beginning and dying-fall denouement do not quite mesh, but I am duty-bound to report that City of Glass was nominated this year for an Edgar award by the Mystery Writers of America.

AUSTER is more successful, I think, in Ghosts. From the outset it is clear that we are in Abstractland. A client named White hires a detective named Blue to follow a man named Black. Gradually Blue realizes he's been ruined. All he can do is stare at Black, eternally writing a book in the rented room across the street, and draw a weekly paycheck. Black and White are probably the same person, and Blue is "trapped . . . into doing nothing, into being so inactive as to reduce his life to almost no life at all."

Auster fleshes out this, well, austere tale with vignettes of old New York. Blue's and White's apartments are located on a street in Brooklyn Heights where "Walt Whitman handset the first edition of Leaves of Grass . . . , and it was here that Henry Ward Beecher railed against slavery from the pulpit of his red-brick church." He tells the story of the invalid Washington Roebling, who presided over the construction of the Brooklyn Bridge from his house in the Heights, with forceful economy. But then Auster's prose is always economical -- clipped, precise, the last word in gnomic control.

The syndrome of being obsessed with and paralyzed by an idea you've talked yourself into seems a particularly European one, not viable on a continent where you can easily pick up and desert your past. That is, until now. Auster, who has spent several years in France and edited The Random House Book of Twentieth-Century French Poetry, has brought the ide'e fixe mentality home. In his detectives who degenerate beyond the standard seediness into self-jailing voyeurs and bagpersons in the cramped streets of New York City, he has provided a striking vision of contemporary American stasis.