Typically, when an "undiscovered" work of a dead writer turns up, there's a good reason it's been a secret for so long. It was bad, the author knew it and so kept it locked up. Fortunately that's not the case with "The Notebook of Trigorin," Tennessee Williams's recently unearthed "free adaptation" of Anton Chekhov's "The Sea Gull." Though a little too pumped up in places, "Notebook" isn't bad at all.

But the real "discovery" is the Keegan Theatre's elegantly restrained production. Nicely shaped and paced, carefully attuned to the nuances of unhappiness, it slowly works its way inside you.

The main reason "Notebook" appeals is that Williams didn't made any radical alterations. The plot is the same: During a visit to her brother's country estate, the famed Moscow actress Irina Arkadina (Rena Cherry Brown) and her lover, the writer Trigorin (Ian LeValley), without ever fully realizing it, essentially torment and ruin those who care most about them. There are subplots of misdirected and unrequited love among the other characters, whose collective misery forms the atmosphere of the play.

Little of this, however, happens overtly. The world according to Chekhov is, on the surface, one of routines and habits buffeted by winds of vanity and humiliation, all very casual, all very normal and all very horrifying: The real devastation is internal. Irina, for example, thinks she is the most loving of mothers when she blithely tells her son, who's desperate to become a writer, that he has no talent. Then it's off to dinner.

To this Williams has added, well, call it Tennessee Gothic--some homosexuality, blackmail and the occasional random act of naked cruelty. The principal effect is that the characters and their actions are bolder in places. This helps undercut some of Chekhov's unwieldy symbolism (oh, that sea gull). But this also makes it harder to believe that the characters aren't aware of the havoc they wreak. The lack of awareness in Chekhov's characters has always been what made them so real--and dangerous.

Mark A. Rhea, the director, wisely plays against the overdone moments (except for the ending, unavoidable because Williams has rewritten it to leave no doubt as to who's responsible for everything). In general, though, Rhea keeps things muted by emphasizing the main characters' utter self-absorption, often revealed through the smallest but most telling of gestures.

When, for instance, Irina has trouble reading something, Trigorin silently offers her his glasses--with just a trace of snideness. She recoils from them as she would from a birthday card revealing her age. As written, though, their conversation is all very pleasant.

The acting is consistently solid in the main roles and in most of the supporting ones. Brown and LeValley, in particular, give a clear sense of how egotists might somehow need and care for someone. Similarly, you get that sense from Jeremy Beck, as Irina's son Constantine; Kerri Rambow, as Masha, the servant's daughter who's in love with him; and Michael Patrick Smith, Masha's husband, who would give anything to have his wife to look at him the way she looks at Constantine. Also giving respectable performances are Stan Shulman, Timothy Hayes Lynch and Daniel Lyons.

The Keegan Theatre is still relatively young and small-budgeted, and you can see this in places. Some of the other actors could use more training and experience; the design work is uneven. The production also begins rather loosely. But it soon pulls together and gradually draws you into a world that is sensitively and impressively evoked. This is a melancholy chamber piece, and its sad melody will still be playing in your head when you leave the theater.

The Notebook of Trigorin, by Tennessee Williams, an adaptation of Anton Chekhov's "The Sea Gull." Directed by Mark A. Rhea. Lighting, Dan Martin; set, George Lucas; costumes, Susan Chiang. With Kit Young, Linda Jean Chittick, Joyce Peifer and Joseph Baker. Through Nov. 14 at Keegan Theatre in Arlington. Call 703-757-1180.

CAPTION: Ian LeValley as Trigorin and Rena Cherry Brown as Irina Arkadina in "The Notebook of Trigorin."