It is among the more remarkable scenes in Shakespeare's "Richard III": The monstrous title character seduces Lady Anne beside the bleeding corpse of her father, whom he has only recently butchered along with her husband. She spits in her suitor's face and calls him "lump of foul deformity," but in due course lets him slip a ring on her suddenly pliant finger. He gloats over his seemingly impossible triumph.

At the Shakespeare Theatre at the Folger, Stacy Keach, playing Richard, sums up the moment in a single gesture: a good-natured shrug, as if to say to the audience, "See how easy this is?"

Easy indeed -- for Richard's is a world, in the last days of the 15th-century Wars of the Roses, where the bigger the lie, the greater its success; where the body politic and its individual members have a limitless capacity for self-deception; where compassionate rhetoric serves to cloak brute force; and where even a limping hunchback, if his falsehoods are sufficiently ruthless, can be an irresistible lady-killer, not to mention king. It is a world, in short, of smoke screens. At the Folger, where "Richard III" began an eight-week run last night, the blood-red stage is enveloped in a perpetual haze (actually Roscolux fog).

For his season opener, Folger artistic director Michael Kahn has devised a rollicking spectacle -- replete with lusty knifings, hearty kicks to the groin and a few deft tosses of a severed head -- in which three hours scramble by like three breathless minutes. It is also visually arresting, with a prisonlike set, evoking a kind of architectural tyranny, designed by Derek McLane, and ominously glinting costumes by Merrily Murray-Walsh. The sheer vigor of the production, and Keach's masterly portrayal of the villainous Duke of Gloucester, excuse a multitude of mostly minor sins, mainly to be found in uneven performances from a not always dependable supporting cast.

Keach, whose pedestrian forays into movies and television belie his impressive background as a classically trained stage actor, plays the murderous protagonist against type, as a kind of malign fool. He mines the character for blackest comedy (there are more than a few laughs in this production) while commenting cynically -- and perceptively -- on humanity as he finds it. Although he occasionally strikes a note of low camp -- one thinks of a comic miscreant as portrayed by Jack Nicholson -- it is an admirably disciplined performance, simmering with pent-up energy.

In the production's first image, an artful stroke of shorthand revealing Richard's basic nature, his misshapen silhouette looms on a heraldic banner center stage, savagely stabbing the prostrate figure of King Henry VI. When next we see him -- after an introductory scene recounting the enthronement of Richard's brother Edward IV, appropriated by Kahn from the text of "Henry VI, Part III" -- Richard is ambling along a metal catwalk, a crude orthopedic brace on his right leg, and delivering the soliloquy that begins, "Now is the winter of our discontent. ..." (Kahn has chosen to augment this famous speech with snippets from "Henry VI, Part III," an improvement that strikes at least this reviewer as more whimsical than necessary.) Keach has said that he imagined Richard as a cross between a chameleon and a crippled racehorse, and he moves with animal grace during his climb from duke to monarch. In the first half of the production, which dramatizes that ascent, there is a dash of swashbuckling hero about him, a perverse sense of fun and devil-may-care. With his open-faced smile and amiable laugh, he seems positively jolly -- in his frequent asides to the audience -- as he goes about eliminating rivals, betraying confederates and turning the truth on its head. Keach adroitly conveys Richard's tortured duality of preening narcissism, covering both his arms with celebratory kisses after his conquest of Lady Anne, and bitter self-revulsion, bleakly acknowledging just before his end, "Alas, I rather hate myself. ..."

In the second half, which depicts Richard's swift fall, the bonhomie evaporates, beginning with the moment when he arrogantly casts off his leg brace, as though his just-acquired crown could cure his afflictions, and bellows with pain as he tries to walk unassisted. Through it all he manages to project an aura of naked power and sheer force of will, in contrast to the feeble maneuvering, or vulnerable innocence, of nearly all the other characters who slip into his thrall. The show is never so engaging as when Keach is on the stage.

Among the other characters, Ted van Griethuysen as the unctuous Duke of Buckingham, Richard's partner in crime, Floyd King as the weak-minded, petulant King Edward (and doubling briefly, after Edward's death, as a scrivener), Edward Gero as Richard's "simple plain" and thus doomed brother the Duke of Clarence, Robert Sams as the sycophantic Bishop of Ely, and Lynnda Ferguson as the accommodating Lady Anne all turn in workmanlike performances.

Rebecca Thompson brings clear-eyed unsentimentality to the role of Richard's long-suffering mother. But as Queen Elizabeth, King Edward's ambitious widow, Franchelle Stewart Dorn is less effective. She greets the news of Richard's murder of her two sons, the Prince of Wales and the Duke of York -- played by child actors who have the usual difficulty getting their tongues around the Elizabethan iambs -- with a display of world-weary acceptance. The portrayal seems at odds with the horror of these pivotal murders, a crime distinctly more evil than any of Richard's others -- after which his destruction can be the only satisfying dramatic conclusion.

The callow, earnest Earl of Richmond, played by John Patrick Rice, has raised an army to depose him, and takes the role of avenging angel. At the end, Keach is still the most compelling presence on the stage, swinging his leg brace as a weapon of last resort before falling to his enemy's sword.

Richard III, by William Shakespeare. Directed by Michael Kahn. Sets, Derek McLane; costumes, Merrily Murray-Walsh; lighting, Howell Binkley. With Stacy Keach, Floyd King, Edward Gero, Matt Jones, Dan Cameron Lowe, Heidi Guthrie, Rebecca Thompson, John Patrick Rice, Rosemary Murphy, Lynnda Ferguson, Franchelle Stewart Dorn, Carter Reardon, Gregory L. Williams, Jose Luzarraga, K. Lype O'Dell, Ted van Griethuysen, Emery Battis, Robert Sams, Bill Grimmette. At the Shakespeare Theatre at the Folger through Nov. 10.