In the final moments of "A Distant Country Called Youth," a one-man show recounting the early life of Tennessee Williams through his letters, the magnetic Richard Thomas reads from a missive by Williams to his agent, in which the playwright is excitedly describing the plot of the new play he's writing.

That play, whose working titles included "The Poker Night" and "Blanche's Chair in the Moon," was about two sisters, Blanche and Stella, and "the remains of a fallen Southern family." Of particular interest, Williams noted, was Stella's husband, a "coarsely attractive, plebeian" man, a character on whom the playwright had also conferred a name: Ralph.

The mention of "Ralph" gets a healthy laugh in the Kennedy Center's Terrace Theater, where this gentle and enlightening production, adapted and directed by Steve Lawson, opened last night for the first of just four performances. The show, the latest installment of the center's four-month festival, "Tennessee Williams Explored," closes after a matinee tomorrow. Like so many of the letters Thomas reads, this one with an embryonic reference to Stanley Kowalski allows us to draw close to Williams at the thrilling time in his evolution from aspiring talent to literary giant.

Based almost entirely on Williams's letters to family and friends, magazine editors and theater producers, "A Distant Country Called Youth" catalogues with a refreshing minimum of artifice the state of Williams's mind and art in the formative years of his career. The period it encompasses, 1927 to 1945, takes the callow Williams from teenage experiences, such as an eye-opening excursion to Paris with his grandfather, to the false starts of his young adulthood, such as the failure of his play "Battle of Angels," through the first great success of his dramatic life, the triumphant Broadway opening of "The Glass Menagerie" with Laurette Taylor.

Thomas may after all these years still be best known as John-Boy Walton, but he's always been a stage actor of terrific poise and passion, and he brings those qualities warmly to the fore in the Terrace. Reading from notebooks on music stands positioned near the edge of the stage, and employing the accent of a refined Southerner, Thomas seems to know just how much actor-y interpretation to impose on Williams's words. By the end of the 80-minute production, he's created a character and established an intimate connection with the audience, without putting a distracting filter on the dramatist's own voice.

"A Distant Country Called Youth" touches on many of the themes and traits for which Williams was known: his sexual appetites, his work ethic, his devotion to his mentally ill sister, Rose, his love of the nomadic life. He writes at one point that he'd rather "starve in a jungle than grow fat in a cage." Lawson excerpts letters that reveal the playwright's ambition -- "They call me the 'gentile Clifford Odets,' which is quite a compliment in the New York theater," he writes to a relative -- and others that spotlight his fascination with the seamy side, as when, in a memorable note, he relates an encounter with Juanita, "queen of the male whores of Mexico City."

Lawson rolls out the letters in chronological order, an approach that makes narrative sense even if in its early stages, the show proves a little heavy going. It would probably take a closer reading of the letters of Williams's adolescence to get a truer -- and more involving -- sense of his development as a writer. The production takes on more urgency as it begins to explore the territory with which an audience is likely to be best informed, the plays and the flowering of his theatrical career.

It's great fun, for instance, to get Williams's jaundiced perspective on the dreariness of a stint in Hollywood, trying to jazz up a cliche-ridden script for Lana Turner, or his horror at the suggestion of Joan Crawford as a casting choice for one of his plays. Similarly, his revulsion at menial jobs, as when he ushered at a Broadway movie palace, brings out an entertaining penchant for the jugular. "To love the masses," he writes, "you want to observe them only in the abstract."

You'd desire no less accomplished an actor than Thomas as an escort through this interesting material. He recites it all with a relish that winningly sheds light on a great writer's joie de vivre.

A Distant Country Called Youth, adapted and directed by Steve Lawson, from "The Selected Letters of Tennessee Williams, Vol 1: 1920-1945." Lighting, Martha Mountain. Approximately 80 minutes. Through tomorrow at the Kennedy Center Terrace Theater. Call 202 467-4600 or visit www.kennedy-center.org.