Michael Frayn, the decent British playwright, puts me in mind of Harry Lime, the indecent American crook. In “The Third Man,” Orson Welles offers Harry’s rancid view of life: The Borgias gave Italy 30 years of war, murder, and terror, but yielded Michelangelo, Leonardo, and the Renaissance. “In Switzerland,” he purrs to Joseph Cotten, “they had brotherly love – 500 years of democracy and peace – and what did that produce? The cuckoo clock.”

I like to picture Mr. Frayn in Cotten’s shoes, taking this in. “Yes, well,” I imagine him murmuring, a little impatiently, as Harry smirks away. “Just what is wrong with the cuckoo clock?”

“Democracy,” which opened last night at the Brooks Atkinson, confirms Mr. Frayn’s status as the bard of our dramaturgical Switzerland, our most passionate devotee of cuckoo clocks. Six years ago, Mr. Frayn wrote a play about the race to build the atomic bomb. It concerned not the frenzy of the Manhat tan Project or the horrors of Nagasaki, but an inscrutable conversation between two physicists in Denmark. Even then, “Copenhagen” devoted as much energy to the science of Bohr and Heisenberg as to the momentousness of their encounter.

Now Mr. Frayn has turned to German politics. You won’t catch the Reichstag burning in “Democracy,” nor will you see Hitler sending himself to hell; that would smack of Borgia melodrama. Mr. Frayn’s subjects are Willy Brandt, the first Social Democrat chancellor of West Germany, and his trusted aide Gunter Guillaume, who was an East German spy.

The cloak-and-dagger betrayals may sound explosive, but Mr. Frayn keeps the lid on tight; next to this play’s understated seriousness, the average Stoppard script is cheap laugh-whoring. Mr. Frayn uses Brandt, Guillaume, and their cohorts in 1970s Bonn as a way to get at his real subject: “the complexity of human arrangements and of human beings themselves.” A little dull, they’ll say – the people who don’t like it. They’ll be right, but they’ll miss the point. Dullness, in the hands of Mr. Frayn, becomes almost a positive virtue. His play is sensationally dull.

Mr. Frayn has written with great breadth over the years, producing shelves full of novels, nonfiction, and plays, including the diabolically clever metafarce “Noises Off.” But his recent work relies on one spindly technique: personification. In “Copenhagen,” Heisenberg became the exemplar of his uncertainty principle. Bohr’s wife says he has a talent “for always being in more than one position at a time, like one of your particles.”

The new play shows how democracy-the system of reconciling irreconcilable goals-operates in Germany, and in Germans. We are each of us a democracy, the play argues, a mass of conflicting perspectives, divided loyalties, contradictory motivations. Brandt himself is charismatic but brooding, moody, and various. “So many people, with so many different views, and so many different voices,” he muses. “And inside each of us, so many more people still, all struggling to be heard.”

Maybe this makes the play sound ponderous; it’s not. Guillaume insinuates himself into Brandt’s service amid the flux of parliamentary politics – not always thrilling, but fluid, and occasionally riveting. (Among political junkies, the play’s appeal may border on the erotic.)

We don’t linger in the Brandt family backyard, or meet any wives or children. A two-story office dominates the stage. This is where Brandt and his advisers manage affairs of state: West Germany’s West Wing. Off to one side sits Guillaume’s minder, Arno Kretschmann. Even as he wraps Brandt and his advisers around his obsequious fingers, Guillaume will lean out of his scenes to give Kretschmann a running commentary. Characters sometimes skip from dialogue to narration to post-facto reminiscence on consecutive lines. It gives the play a lively theatricality.

In Brandt and Guillaume, Mr. Frayn has created two of the richest, most challenging roles in recent memory. Brandt is the quieter of the two, and the more difficult. He is described in quasi-mystical tones as a consummate politician, with a great memory, a fondness for jokes, and a knack for seeming “to talk to you alone.” Act One, when Brandt is riding high, calls for the charisma of Bill Clinton, another scandal-plagued leftist in search of the “New Middle.” In Act Two, when Brandt is plagued by self-doubt, he sounds like Richard II.

James Naughton gets Brandt’s smoothness and some of his melancholy. The hidden recesses, however, escape him. What ought to be sphinx like depths are merely layers of obscurity. He doesn’t project the air of a conflicted messiah, more like a musical theater star waiting for his cue to sing. In Mr. Naughton’s defense: Try as I might, I can’t come up with an American actor likely to fare much better.

Guillaume has to provide the show with romance. As he weasels his way closer to Brandt, he begins to admire and love him, even as he stabs him in the back. When he learns that Brandt wants him replaced, he starts rationalizing, much like a schoolboy whose crush has been, well, crushed: “I was hurt. Naturally. But I put it behind me. It was the depression speaking.”

Eager and boyish, Richard Thomas’s Guillaume shows complete fealty to Brandt. But his Apollonian devotion lacks a crucial tinge of Dionysus. In Terrence McNally’s “Prelude and Liebestod” earlier this year, he showed he can swoon when he needs to. He needs to, here.

The best moments come from the delightful secondary characters-the party hacks and functionaries, the surf on which Brandt and Guillaume bob. Keeping the ruling coalition together, bribing their way out of a no-confidence vote: Everybody has an interest in propping up Brandt, even the people who can’t wait to tear him down.

Leading the way is “Uncle” Herbert Wehner, the head of the party. The role is consummately realized by the terrific Robert Prosky. With tiny eyes, swelling jowls, and irrepressible delight in tugging the levers of power, he gives Broadway’s most satisfying supporting performance since Denis O’Hare in “Take Me Out.” John Dossett is very good as Helmut Schmidt, that consummate beta-male – the politician waiting his turn. As the canny spymaster Kretschmann, Michael Cumpsty is admirably bemused. Richard Masur flails as the hapless official who vetted Guillaume, but Lee Wilkof, as the German equivalent of Nixon’s plumbers, does his best work in years.

Only in the sparkling work of Messrs. Prosky and Cumpsty does the show convey a vital sense of politics, not as machine, but as art – and as blood sport. Director Michael Blakemore lets too many juicy moments slip by. When the party begins to suspect that Guillaume is a spy, Brandt agrees to watch him. The play turns into a marvelous game of cat-and-cat. Or it would, if Mr. Blakemore ratcheted up the tension between the two men. He wouldn’t have to go over completely to the breathless Borgia approach. A lurid, excitable moment here and there would suffice.

As it is, Mr. Frayn’s play satisfies, even with its dullness. Each of its quiet revelations is a fresh retort to Harry Lime: If a room is quiet enough, says Mr. Frayn, and you listen hard enough, even a cuckoo clock can thrill. The most startling line in the play is so quiet you might miss it. When Brandt concludes a treaty with the East Germans, Guillaume joins in the celebration. His minder tells him Berlin only agreed to sign “because you helped us to trust him.”

It’s almost subversive: Guillaume helps to bring down the play’s hero, but he’s no villain, not even the sympathetic, he-had-his-reasons kind. He is an active force for good here, and an active force for ill. The triumph of Mr. Frayn’s play isn’t just representing complexity, it’s teaching us to savor complexity – to admire all those lovely shades of gray.

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