For baby boomers, Chekhov has always been the most relevant of classical playwrights. There is something in his characteristic mood -- the groundless yet touching melancholy, the obsession with missed opportunities, the yearning for bedrock, the hopeless ineffectuality -- that speaks directly to this generation in another land, another time. It's an elusive mood, and the great triumph of Nikita Mikhalkov's "An Unfinished Piece for Player Piano," a 1977 film premiering today in Washington, is that it captures it effortlessly.

Based on "Platonov," Chekhov's first published play, the movie takes place during a day at the country estate of Anna Petrovna (Antonia Shuranova), a widowed and impoverished aristocrat who is entertaining family and friends. Her stepson, Sergei (Yuri Bogatyrev), speechifies on the "moral strength" of the peasantry; his wife Sophia (Elena Solovei) rows on the lake. An impressively mustached suitor sits meekly at her side; and the Doctor (director Mikhalkov), already drunk (though it's only morning), entertains them from the terrace with blasts from a shotgun and mad improvisations on the violin.

Enter Platonov (Alexander Kalyagin), and the show begins. The structure, and the catalyst, is built on a pyramid of love triangles: Platonov has had affairs with both Anna and Sophia, so as the plot unwinds, he becomes the object of jealousy for Sergei, the suitor, and his wife, a stolid, slightly stupefied young thing (Eugenia Glushenko). Add a doddering grandfather, a boorish blowhard (Oleg Tavakov), an abused servant and a quietly confident middle-class creditor, and the cast is complete.

They sit around. They drink a great deal. They play foolish parlor games (including one that involves sending the servant out into a gale to find a pig so that the doctor may ride it around the house). They entertain each other with songs and masquerades. They pontificate (oh, how they pontificate!), thrilled not with ideas but with the idea of ideas, the faddish soapboxes of Darwin, women's rights, peasants' virtues, the cult of hygiene.

And most of all, they reminisce: Anna, about the days when she could keep both estate and honor, without debts; Sophia, about her ambition to be an actress; and Platonov, about the days when, in Sophia's words, "We all thought he was a second Byron," but who is now, not a poet, but a schoolteacher with an undistinguished marriage, much paunch and little hair -- in short, that most horrible of horrors, an "ordinary man."

"Let's leave the past alone," someone says; and of course, no one can. Even the present is seen from the perspective of the future -- in a sense, they live life as the past to come. "Is it possible," Platonov says, "that we'll laugh and weep over these days, 10 years from now?"

Chekhov depends on seamless shifts in tone -- from comedy to drama, and ultimately, to a broad but unsentimental sympathy -- and Mikhalkov orchestrates it with awesome control. Filigrees of slapstick are added economically. The movie slowly contracts from long shots and a legato, panning camera, building, as the conflict waxes, to tighter shots and then close-ups cut in montage. The pastel images are luminously gauzy, the lace and linens palpably soft, the greens of the spectacular scenery fading before your eyes -- it's the prettiest film seen here since "A Sunday in the Country."

And Mikhalkov's camera can be adventurous as well in understated ways. When the party travels upstairs from the living room to the terrace, for example, Mikhalkov follows from outside, craning up on the exterior of the house. The climactic scene between Platonov and Sophia fades to black and white -- what is ashes in his mouth becomes ashes in our eyes.

"An Unfinished Piece for Player Piano" is buoyed by a cast that is uniformly excellent, particularly Kalyagin, whose performance is full of nervous pain, spitting sarcasm and wild left turns (including a mad, clownish dance down a hill); the broad-bellied Tavakov, who booms and fumes like an overheating boiler; and Solovei, whose sloping eyes and edgy glances suggest a Russian Diane Keaton.

"All's lost!" shouts Platonov at the end. "I'm a nonentity! I'm 35!" Who among us who is 35 cannot recognize this self-torture? What takes "An Unfinished Piece for Player Piano" beyond so much contemporary drama is the skepticism with which it dissects both the glorified past and the feelings of inadequacy that grow out of it; its honesty gives it real power, a poignance that isn't stage-managed. The solution, for Chekhov and Mikhalkov, is love, pure and simple. And they have you believing it, if only for a minute.