By Charles Baxter

Norton. 223 pp. $17.95

A character in "Westland," a story in this superb new collection of short fiction by Charles Baxter, goes out of his way to do a good deed and sets off an unlikely but not implausible chain of events that betters his own life. Warren, a depressed Detroit professional sent out for groceries by his wife, takes a detour to the city zoo where he meets up with a rebellious 15-year-old who has just spent the night there. Warren feeds Jaynee a cheeseburger, then squires her to the safety of her father's house in suburban Westland.

By extending the hand of friendship to Jaynee and her beer-guzzling, grease-monkey father, Warren performs a small act of valor. Indeed, small acts of valor thread through "A Relative Stranger," a taut and moving collection of stories -- the third by Baxter, who teaches at the University of Michigan and has published one novel and, just this year, a volume of poetry.

Not that they are one-dimensional do-gooders, these mainly middle-class characters who try to cut through the acrid, ever-polluted air and frightened, cynical spirit of present-day Michigan. Usually their good Samaritanism comes in the wake of the depression, angst and anger they are in the process of working through. In fact, the only possible candidate for the unambivalent do-good designation is elderly social activist Clara Fenstad -- a longtime champion of civil rights and social change -- who, in the story "Fenstad's Mother," sits in on her son's evening extension class where she befriends a young black student whose ego she seeks to bolster. Later, in a coffee shop, Fenstad's mother offers her good winter coat to a deranged bag lady, despite protests by her son.

More typical of most of the characters is the naive idealism of Cooper, a conscience-stricken baby boomer whose efforts to shatter barriers between the classes backfire. In the story "Shelter," Cooper volunteers at a homeless shelter, where he befriends Billy and brings him home to meet his family. When Billy launches into an unprovoked tirade against his hosts and their cozy domestic scene, Cooper whisks him back to the shelter.

"As he expected," Baxter writes, "Christine was waiting up for him and gave him a lecture, in bed, about guilty liberalism and bringing the slime element into your own home." The contrite Cooper -- who sees that his young son, frightened of his zealous charity, has hidden his piggy bank under his bed -- insists he will never repeat the mistake.

Several of Baxter's characters are exquisitely rendered, including the aforementioned mother of Fenstad, and Saul Bernstein, a tortured high school teacher in the story "Saul and Patsy Are Pregnant." So too is Oliver Harris, a young man in the title story, whose irresolution about his adoption in infancy comes to a head when his biological brother, hitherto a complete stranger, barges in on his life.

"Every adopted child fears and fantasizes getting a call like this announcing from out of the blue that someone in the world is a relative and has tracked you down." Initially reluctant to meet the persistent man, Oliver relents. "I was in that bar one hour before I said I would be, and my feelings were very grim. ... I didn't want some strange sibling checking out the way I close the distance or blink behind my glasses while my eyes adjust to the light. I don't like people watching me when they think they're going to get a skeleton key to my character."

It takes precious little observation to perceive Baxter's enormous concern for a whole host of environmental problems, from poisonous chemicals infiltrating our food chain to the effects of unguarded industrialization on the Michigan countryside. Baxter's is a post-feminist world, in which men need no longer struggle with the growing personal and professional power of women, who often as not achieve more than their menfolk. Baxter's men tend to adore women, and they are more likely to be haunted by their mothers than their fathers. Some, like Saul Bernstein, as he watches his wife transplanting pansies in their garden, suffer from gender guilt.

"She liked being a woman. She liked it in a way that, Saul now knew, he himself did not like being a man. There was the guilt, for one thing, for the manly hobbies of war and the thoroughgoing destruction of the earth. Patriarchy, carnage, rape, pleasurable bloodletting and bloodsport: Saul would admit a gender responsibility for all these, if anyone asked him, though no one ever did."

Here and elsewhere, a reader suspects the author of committing that all-too-common transgression in contemporary fiction of intruding on the voice of the character. Is this really Saul thinking or Baxter preaching? Likewise in "Shelter," in Billy's invective against Cooper and Christine's middle-class life, when he belittles their "do-good groups like Save the Rainforests" and rails against destructive yard chemicals, he sounds more like a college-educated environmentalist than an underfed vagrant.

These are trifling bones to pick, though, against the magnificence of the collection, which in this anti-heroic age refreshes a reader with its quiet and ultimately uplifting insistence that strangers can lend a hand (or a cheeseburger) and do make a difference.

The reviewer lives in Carroll County, Va., and is co-writing a book on simplifying one's life.