BOOK REVIEW : Gaining Humanity Through a Life That Grows Darker : POLITE SOCIETY, <i> by Melanie Sumner</i> (Houghton Mifflin/Seymour Lawrence; $21.95, 204 pages)

Her two years serving in the Peace Corps in Senegal have provided writer Melanie Sumner with a world to apprehend and a refractory protagonist to do the apprehending. “Polite Society” sends a young woman from Tennessee marching her ignorant appetites through the elusive, dead-serious complexities of an impoverished African society.

It is a tragicomedy of cultural misapprehension. Darren, like legions of tourists from privileged civilizations--the English once were famous for it, then the Americans and now the Japanese--treats the foreign place as something to see, to experience, to acquire.

In fact, the foreign place sees, experiences and does its best to acquire her ; and to their mutual peril. “Passage to India” was the classic exploration of such a double disaster, and a number of reflections of E. M. Forster’s masterpiece occur in “Polite Society”; among them, the mingling of nightmare and epiphany during Darren’s visit to a cave with a young Senegalese.

Sumner is no imitator; she transforms an old message for a new time, which can use it. Instead of the cultural parochialism of Edwardian England forced up against the bloody myth and magic of the great world, it is Generation X’s equivalent parochialism--its Internet capabilities notwithstanding--that is forced up.

Instead of Forster’s seamless and knowing prose, Sumner writes in a nervy and fragmentary style, its illuminations interspersed with an affectless fog that is almost druggy. It is a style that indelibly renders Darren but it is dangerous to use. The author has taken the risk of alienating her alienated character from the reader; the gamble pays off, finally, as the character is chastened into knowledge and the writing grows into resonance. It is the writer’s way of allowing herself the compassion that, had it come earlier, would have marred the story’s icy edges.

A patina of comedy veils “Polite Society’s” satire, which in turn veils a harsher stratum underneath. Darren is a wealthy brat from Stipple, Tenn.; her father dotes on her as if she were a son, her mother--a former Miss Tennessee--is competitive. Dropping out of college, restless at home, Darren arrives in the predatory maelstrom of beggars, guides and grifters at Dakar airport, to be rescued by a senior--and thus embittered--Peace Corps volunteer.

The in-country training center is a predator’s ball, though it is hard to tell whether the predators are the slim, beautiful and infinitely courtly Senegalese language teachers, or the young American women for whom enchanting seductions are exotic trophies. Darren, who may never have left an itch unscratched, pairs off with Moustafa: utterly hers when he is not someone else’s (one volunteer produces a map with Moustafa’s conquests marked with pins, Peace Corps village by Peace Corps village). He weeps with desire and goes away for a month; he gives her a black eye when she punches him in jealousy; he comes back after she has written a letter “firing” him as teacher and lover; she Maces him.

An American solution, technological and easy to apply. Moustafa is more complicated and, in his way, wiser. Men and women cannot look at each other for long without growing tired, he says; they should both look the same way. Sumner uses him almost as rehearsal for the finest portrait in the book: Yousouf, the lover Darren takes when she is assigned to Dakar.

He works in a bank, has little money, is proud, funny and unexpected. She insists she will not marry him because she could not bear to be a second wife (he is Muslim). “What second wife: on a banker’s salary?” he expostulates. If they do marry perhaps the Ku Klux Klan will come for him, he fantasizes as they lie in bed: “But my Boy will protect me.” Darren is far more macho than he is.

“Polite Society” is told as a series of sketches; we do not know what happens to Yousouf but presumably--after a comically painful visit by Darren’s parents who trek out to pay a call on Yousouf’s mother in a distant village--he fades out of Darren’s life.

It is a life that grows darker. She is an alcoholic, and getting worse. She makes a useless visit to a witch doctor, hoping for a cure. A street beggar knocks her down. She is caught in a street riot. Hiking to a cave, she comes into a danger that is more than physical; it threatens her veneer of identity. And bit by bit, as the veneer slips, she finds herself one more purposeless foreigner, a speck of foam on an African sea. It has only been two years or so, but although nothing explicit is said, we see her aging.

At the same time--and this is the deeper achievement of Sumner’s astute first novel--lines of humanity appear. She begins to wrinkle out from solipsism into history.