In the 1920s and 1930s, the legendary German photojournalist Erich Salomon used to slip unsuspected into the meeting rooms of the great and powerful and take candid shots of his distinguished subjects in moments of bluster or outrage. The English playwright and novelist Michael Frayn does Salomon one better: He slips into the minds of seemingly unapproachable figures – Willy Brandt or Niels Bohr – and gives us not only unguarded expressions but unguarded thoughts as well.

Mr. Frayn is invisible in other ways. Though he has written some 10 novels and about twice as many plays, he disappears into his characters so thoroughly that he seems merely the medium through which they give expression to their deepest fears and longings. This isn’t so much modesty as an uncompromising professionalism. However tangled or convoluted the situation or the plot, Mr. Frayn presents it with such clarity and concentration that all the strands of ambiguity lie starkly before our eyes. He doesn’t resolve his puzzles, nor does he tie them up neatly in a dramatic package. He lets them work on us, long after we leave the theater or close the book.

“Democracy,” his latest play, takes the relationship between German Chancellor Willy Brandt and his trusted aide Gunter Guillaume as its guiding dilemma. Brandt and Guillaume share a close personal bond; yet Guillaume has been passing information to the East German Stasi for years while at the same time making himself indispensable to Brandt. Guillaume is a traitor but what makes him interesting as a character is his genuine attachment to his master. He is, we might say, the most loyal of traitors.

Mr. Frayn’s portrayals have the ring of authenticity; we can believe that we have been admitted to his characters’ most covert impulses. His Brandt, at once magnanimous (in the literal sense of the word) and wretched, comes across as somehow bigger than life, even in his many flaws. But the key to

both characters lies in their relationship with each other, for they are strangely and inseparably linked. Mr. Frayn shows this to us with great subtlety. Brandt was a dedicated womanizer, a trait which brought him into disgrace and downfall, and Guillaume was no slouch in this department, either. Here is a brief extract from a scene in which the two discuss women:

BRANDT

I can see you, Herr Guillaume. Eyeing the girls.

GUILLAUME

What is it about women, Chief?

BRANDT

The way they look at you … The way they look straight into your eyes and you look straight into theirs. The way you can’t understand them. The way you can.

GUILLAUME

The way they smile.

BRANDT

The way they look seriously at you. The way they make fun of you.

GUILLAUME

The way they’re not like men.

BRANDT

The way they are. The way they touch your hand. The way they touch your face. The softness of their touch on your skin. The softness of their own on theirs…. All the different people you can be with them. All the different ways your life might go.

The dialogue here builds into a beautifully paced duet; one finishes the other’s sentences or voices an unexpressed thought the other has not yet uttered. There is an amorous complicity in the exchange; Brandt and Guillaume are like two cats sidling up to each other and purring in mutual pleasure. The key to the exchange, and to the play, is given when Brandt says, “All the different people you can be with them.”

Michael Frayn has remarked that his plays “are all about … the way in which we impose our ideas upon the world around us.” In his novels too, and especially in “Headlong,” which was a finalist for the Booker Prize in 1999, his characters continually come to grief when the world declines to coincide with their stubborn ideas about it. Mr. Frayn might be called a writer of ideas but such a label falsifies his accomplishment. His characters breathe and bleed, and that is what counts in the end.