Jim Leonard's "The Diviners" has been through some changes since last year, when it won a prize as the best original play of the American College Theatre Festival and gave that sleepy event a shot in the hindquarters. Last fall a rewritten version was produced at New York's Circle Rep. Yet another rewrite preceeded Sunday night's opening at the New Playwrights' Theatre.

The play had benefited from this cumulative attention. The second act and the ending have gained in clarity and momentum. But "The Diviners" was an impressive play to begin with, and remains so. Those who saw it last year at the Kennedy Center may have trouble recognizing specific refinements. They should have no trouble recognizing the unusual phenomenon of a fluid, well-realized production in which author, director, designer and cast seem to be working on the same wavelength.

The story is still set in 1932 and in the imaginary southern Indiana town of Zion. (This gives Washington what must be a record total of contemporaneous plays with an Indiana connection -- two. The other is the musical "God Bless You, Mr. Rosewater" at Arena Stage; Kurt Vonnegut is, like Leonard, a Hoosier, and that's where the analogy ends.)

Leonard introduces us immediately (and with an efficiency characteristic of his writing) to the central character, Buddy, an amiable, idiot boy with an obsessive fear of water and a magical ability to find it in the ground or feel it coming from the sky. Then we are introduced to an ex-preacher with the portentous name "C. C. Showers," who comes to work in Buddy's father's garage. Born to a line of preachers, Showers entered the field because, he explains, "a boy comes to be 17 or 18, there's no question asked. Hand him a Bible and turn him loose on the world." But as his career proceeded, he began thinking and preaching at the same time -- two activities that "just do not mix," he had decided. So he has given up divine service in favor of reason. Buddy, on the other hand, has given up reason in favor of divining, ever since the traumatic time when his mother drowned and he nearly did too.

Showers takes a liking to Buddy, and takes it on himself to cure the boy's chronic itching by way of curing his hydrophoabia. But when the townsfolk hear about his success at getting Buddy to soak his feet in warm water and salts, they draw the wrong conclusion, and resolve to get the expreacher preaching again.

Migratory ex-preachers, children with mystical powers and families whose lives are transformed when a stranger signs on as a hired hand -- these are all familiar ingredients. But much of the charm of Leonard's writing is his ability to combine the familiar into the unusual. At its best, "The Diviners" has the evocative, ambiguous force of a tragic folk tale. There are times, however, when Leonard upsets that darkly lyrical mood with incongruous touches. Perhaps as a result of being freed from the constraints of a college production, he has peppered the dialogue with obscenitites that impart a needlessly drab and naturalistic flavor to his play. And in the interests of clarifying motivations, perhaps, he has given Buddy a cliched, out-of-character speech about his guilt over his mother's death. But these are small, as well as arguable, flaws in a smartly constructed, generally enthralling work.

Director Martin Guttenplan keeps things going at a graceful pace, and there is an evenness and control to the acting that suggests a strong relationship between director and cast. Boyce Miller has the right kind of low-keyed, ingratiating manner as Showers. His reversions to preaching -- including one early scene when he resorts to his pulpit voice in the very act of renouncing the pulpit -- are persuasive and often funny. What's more, Miller and Paul Preston, a plausible-looking, plausible-sounding Buddy, seem to have substantial stage rapport. The other members of this unusually apt-looking cast give performances that are workmanlike, at least, and often more than that. And they are sturdily supported by Douglas A. Cumming's fanciful, multiterraced set.

THE DIVINERS, by Jim Leonard; directed by Martin Guttenplan; scenery by Douglas A. Cumming; lighting by Greg Basdavanos; costumes by Liz Bass; with Joe Glenn, Ernie Meier, Paul Preston, Michael S. Willis, Barbara Rappaport, Jenny Brown, Boyce Miller, Hank Jackelen, Mary Saloschin, Dianne Couves and Kathleen Webber. At the New Playwrights' Theatre through June 28.