Patrick Stewart is a commanding, fascinating Othello in the Shakespeare Theatre’s production of this saddest of all the Elizabethan tragedies. Theatergoers, particularly those who saw Avery Brooks’s volcanic performance here seven years ago, might have wondered whether Stewart, an actor of formidable power but not much heat, was the right choice for the jealous-mad wife-murderer who at one point says of his bride, “I’ll chop her up in messes.”

But the canny Stewart knows not only how to play to his strengths but also how to play his limitations so that they serve as strengths. He creates a beautifully delineated portrait of a plain-spoken man of action who turns out to have rotten nerves (someone should cast him as Hemingway). This Othello collapses rather than explodes, and the result is as frightening as any eruption, as if we were caught in the crushing fall of some great building.

Othello is the most fully sympathetic of Shakespeare’s tragic heroes. The complex, ambivalent, brilliant Hamlet somehow disdains our sympathy, while Macbeth is a homicidal careerist and Lear a spoiled jerk. Othello is truly great-souled. In former centuries, Othello was said to be vulnerable to Iago’s machinations because he was black and therefore impulsive. Nowadays, he is said to be vulnerable to those machinations because he is black and therefore has learned self-hatred from the ruling white society. But the reason the play is so painful to watch is that Othello is vulnerable to Iago because he is simply too good to understand him. The Moor can hate and he can kill, but the petty, sneaky nastiness of an Iago is beyond his imagining. He’s a lion brought down by the bite of a rabid rat.

Ron Canada’s middle-aged Iago has had time to brood on his wrongs until they’ve hatched to moral tumors. Straightforward, efficient and careful -- a typical career noncom -- this Iago starts out as one of the most successful renditions of the role I’ve seen. But the character fades as the play goes on. Iago sets in motion a plot with many moving parts -- we need to see him thinking on his feet, always in motion to trap his victim. Canada just plods on. At one point, he makes Iago conscience-stricken at what he is doing to Desdemona, but in the next scene he seems to have overcome this with no trouble. Nothing builds. As his net tightens, this Iago becomes not more frightening but vaguer. It doesn’t help that Canada kept stumbling over his lines, the kind of thing that saps a character’s authority.

It’s good to see Teagle F. Bougere, the talented former Arena Stage actor, back in town to play Cassio, Iago’s unwitting tool. But Bougere doesn’t appear to have made up his mind whether Cassio is a decent fellow or a sulker or some combination of both, and it’s hard to know how to respond to him. Jimonn Cole is broadly funny as Roderigo, which sometimes works and sometimes seems like an outtake from some other play. The delicate-boned Patrice Johnson plays Desdemona as a loving girl, too sweet-natured and too young to understand the foulness that envelops her.

The most startlingly original performance comes from Franchelle Stewart Dorn as Emilia, Iago’s wife. Dorn gives us a browbeaten creature, pathetically in love with the husband who despises her, and afraid of him as well. This Emilia makes a moral journey in the course of the play; she has her own tragedy and heroism.

Jude Kelly’s direction is vigorous, and her production ideas are often impressive, but sometimes she over-theatricalizes. The play opens in a rainstorm, which is supposed to supply mood but really just piques our curiosity about where the drains are and why Roderigo ruins his lovely green velvet suit by sitting down in a puddle. In a brutal, powerfully acted scene between Othello and Desdemona that should be devastating, the lighting is so moody that half the time you can’t see the actors’ faces. Desdemona dies on a bed hung with sheer white curtains so that we can view the action through the thin fabric, watch the curtains flutter down as she dies, and admire the artfully placed splotch of blood that shows up on one of them.

Stewart plays Othello the Moor in his own white skin, bald head scarred with a savage-looking tattoo, while his new young wife, Desdemona, his destroyer, Iago, and the ruling nobility of Venice, where the play begins, are African Americans. The stage couldn’t be more obviously set for some daring, stinging race-reversal, but the potential dynamite fizzles -- largely because race prejudice is only one of several dramatic elements in the script and won’t stand up to being made into what the play is “about.” Of all the characters, only Iago and Desdemona’s father (Darrell Carey) make racially disparaging remarks about Othello. Everyone else either speaks well of him or is mute on the subject. (Even Iago never makes racial sneers at Othello when he’s speaking his mind directly to the audience in his soliloquies: Like any cynic, he plays the race card when it suits him.)

Though lines have been modified to conform to the production (since the soldiers use guns, “Put up your bright swords or the dew will rust them” becomes “Put up your bright arms . . .” and so on), the insults to Othello are left as written and Stewart’s Othello is sneered at as black. For a white audience to see a white actor and character scorned in vicious racist terms could have been a scathing theater experience, but the whole issue just seems confused. What is the audience supposed to think when Stewart, an actor whose mouth is like a slit in his face, is derided with the remark “thick lips”? Or when, pale pate gleaming, he announces in the plummiest of English accents, “Haply, for I am black . . . “? Or when a black actor castigates Othello for his dark-skinned ugliness? If the purpose was to show how foolish and empty racial derogations are, how they’re just words, the device misfires. Racial derogations end up seeming meaningless, even harmless -- surely not what Kelly intended.

So though the Venetian senators look at Othello in disdain and disgust when they find he’s married Desdemona, and the Venetian soldiers, who are black, razz the Cypriot troops, who are white and wear funny-looking orange uniforms, that’s about the extent to which the production grapples with race relations. Fortunately, the play, indifferent to present-day graftings, rolls on its magnificent, terrible way, to dash the audience on the rocks of terror and pity.

Othello, by William Shakespeare. Directed by Jude Kelly. Set and costumes, Robert Innes Hopkins; lights, Frances Aronson; composer, Michael Ward; fights, Rick Sordelet. With Craig Wallace, Michael W. Howell, George Causil, Chad L. Coleman, William Badgett, R. Emery Bright, George F. Grant, Kate Skinner. At the Shakespeare Theatre through Jan. 4. Call 202-393-2700.