For all actors worry about with regards to "process," it's a remarkably complex thing to quantify. The technique, the training, and the tricks are so myriad and complex that in many cases it's probably easier to identify what goes into making a successful marriage. In his play Ten Chimneys, which just opened at the Theatre at St. Clement's in a Peccadillo Theater Company production, Jeffrey Hatcher weaves both concerns together so tightly that it soon becomes impossible to tell which is which.

Of course, such an achievement could only be possible if it focused on Great Actors, and in that respect Hatcher has zoomed straight to the top. His subjects are no less than theatrical deities, and husband-and-wife team extraordinaire, Alfred Lunt and Lynn Fontanne. Dominating the American theatre, in New York and on the road, for much of the first half of the 20th century, they attained a unique synergy both onstage and off as they strove for truth wherever they could find it. It's difficult to imagine more towering, and yet personable, figures around whom to build a charming, slice-of-life romance.

Their presence is only magnified by the performers who play them. Byron Jennings and Carolyn McCormick may lack some of the real duo's sweeping grandeur, but they compensate with rich energy and an irreplaceable authenticity—the two are married themselves, and so inform their roles with that personal history that they never seem to need to work to generate the chemistry between Alfred and Lynn that once electrified audiences. When the couple works their hardest on a scene, repeating it endlessly and at increasing speed as they explore new variations on backstory and emotional shadings on their lines, it's clear that the two onstage affairs being depicted are as symbiotic as they are inseparable.

"Whenever we talk about the theater, we're talking about love," Lynn says at one point, and that could just as well serve as the one-sentence summary of Ten Chimneys. Hatcher investigates everything about how they make union work, and finds that it usually involves discovering characters or creating characters from the real stressors they're facing. Over the course of a few days in summer of 1937 and one night eight years later, all at Alfred's Wisconsin manor (which gives the play its title), every reference they make about the production of The Seagull they're planning has a secondary meaning regarding the way they work and live together, and unraveling the pieces of the puzzle is a gentle but definite delight.

What's less effective is pretty much everything else. Aside from its impact on the Chekov everyone is muddling through, the subplot fling between Alfred and his Nina, Uta Hagen (Julia Bray), is never especially compelling. You never doubt Alfred's feelings for his real partner, or that Uta sees in his eyes only a mentor and not a Lothario, and the tension this summons is minimal. Sydney Greenstreet (Michael McCarty), also on hand, contributes little to the texture of the evening beyond a few ruminations about the wife he's sadly separated from. And Alfred's mother Hattie (Lucy Martin) barks a few potent one-liners now and then, but is mostly just there to contrast one male-female relationship with another.

It's a lot of excess for a tale that would benefit most from a lean treatment, and it doesn't leave an ideal amount of breathing room. Even under these circumstances, the supporting actors, who also include John Wernke as Alfred's step-brother, are all fine if seldom luminous, with Bray particularly good at conveying a long-dead live-performance language but less adept at suggesting another kind of supple stardom simmering just beneath her skin. The set and lights (by Harry Feiner) and costumes (Sam Fleming) are attractive but workmanlike, capturing a general sense of the people and place without ever really fully transporting you. Much the same is true of Dan Wackerman's efficient but flat direction that easily guides scenes from beginning to end but rarely allows them to pop.

Jennings and McCormick do most of the heavy lifting, and do it impressively well. Without ever lapsing into haughtiness, they display an intriguing all-American regality (no small accomplishment for McCormick, given that Fontanne was British) wrapped in a cloak of Everyman recognizability. Though measured and thoughtful in their speeches and their deliveries, they're never overly deliberate. You never have anything less than the impression that both are, in fact, such skilled actors that new thoughts and new souls pop up inside them with an almost continuous frequency.

Their portrayals buoy and center Ten Chimneys, letting their characters' work be exactly what outstanding theatre work should always be: simultaneously mundane and magical. It's difficult not to wish that Hatcher devoted even more attention to Lunt and Fontanne, so that we could come to understand them, and other extinct creatures like them, even better. But when Jennings and McCormick are at their hottest, you understand every nuance in the composition of theatrical legends, whether what makes them different from us or what makes them just like us, better than you do with almost any other play touching on the topic.

Ten Chimneys
Through October 27
Theatre at St. Clements, 423 West 46th Street
Tickets and current schedule ovationtix.com