The phrase “going postal” says it all. Any time there’s a sniper attack from a water tower in small-town America, so the urban myth has it, you only need look as far as the nearest disgruntled postal worker to find the mail-order rifle and the burning grudge against mankind. Friendly, uniformed mailmen with hair-trigger tempers — it’s a vivid combination of the murderous and the mundane.

The central figure of Edmond, David Mamet’s modern morality play, might not be a mailman, but he is a similar mix of the homicidal and humdrum: a “solid” but insignificant drone who flips into a frenzy of sex and violence after a fortune-teller tells him: “You are not where you belong.” Thanks to such writers as Michel Houellebecq and Bret Easton Ellis — not forgetting the likes of Harold Shipman — the idea of the ordinary man with a dark inner life has become increasingly resonant since Edmond was first staged in 1982. “Going postal” — not to mention the enduring media fondness for such formulations as “road rage” and “air rage” — shows a society now used to irrational anger, unpredictable tempers, mysterious impulses. The suspicion that anyone can succumb to their basest desires, that politeness and political correctness are merely a loose cover for a million seething prejudices, hatreds and resentments, is perhaps not quite as shocking as it might have been 20 years ago.

Yet in Edward Hall’s bracing production, the combination of Mamet’s crazed verbal patter and Kenneth Branagh’s febrile central performance creates a compelling, invigorating 80 minutes, a magnesium flare of rage, wit and turbulent philosophising that is as exhilarating as it is disturbing. Badly done, it would have been reminiscent of Falling Down, Michael Douglas’s flawed film about a middle-aged man turned moral vigilante. Directed and performed with skill and curious grace, however, it becomes a startling examination of human nature’s grimmest corners.

Branagh certainly knows how to make an entrance. Absent from the London stage while pursuing directing, film and television interests, he makes a blockbusting return. His National Theatre debut sees him play Edmond Burke, 37-year-old husband, worker and citizen — and the vehicle for Mamet’s darkest fears for humanity. After his encounter with the fortune-teller, Edmond spends 23 short and brutish scenes descending into a moral wasteland, smashing through structures that have held him in place for so long. He leaves a sterile marriage to his brittle, bored wife (Tracy-Ann Oberman) in a scene of brilliant concision. Her idea of a nice evening conversation is to complain “The girl broke the lamp” — an impeccable snapshot of Edmond’s life, shorthand for a certain kind of marriage, class and set of prejudices. Audiences may laugh as he tells her he is never coming back, but it’s nervous laughter. This is a chilling portrayal of the most impotent rage of all: the fury at wasting your life.

Edmond heads out on the mean Manhattan streets in search of sex, as brothels, bars and by-the-hour hotels all flash by on Michael Pavelka’s lurid, neon-lit revolving set. There’s a throng of supporting actors on hand to bring the city to life, bright performances lighting up the unfriendly stage like Times Square: the shrill Jersey peepshow girl (Nicola Stephenson); the camp hotel clerk (Stephen Greif); the street-corner shill with the find-the-lady shtick (Adam Levy); the canny, business-minded whore (Rebecca Johnson). As the night and its terrors wear on, Edmond fatally buys a knife in a pawnshop, but it’s the little humiliations and frustrations that exacerbate his problems: the desk clerk won’t let him use the phone, a woman on the subway ignores his attempts to engage her in conversation. “What am I? A stone?” he yells. “What am I? A dog?” Even those audience members not experienced in homidical rages are likely to understand this part of his aggression.

Which, when it comes to designing a symbolic everyman, is partly the trick. Branagh is superb at portraying these mood swings, born out of a self-righteous disgust, nourished through self- justification. It is Edmond’s quest to feel more alive that finally makes his situation spiral out of control — he kills a pimp in a torrent of racial abuse, picks up an actress waiting tables at a diner (Nicola Walker, excellent as the mentally frail lost soul), and, back at her apartment, the real crisis comes. Branagh portrays the true Edmond as the one who pants like an animal over his kills, uttering strange bestial cries, saturated in sweat and adrenaline.

Following his work in the chilling television play Conspiracy, this is another distinctly uncuddly role, making a very good case for the fact that he’s no longer lovely Ken bringing Shakespeare to the people with his Hollywood friends. Here, he refuses to ingratiate himself with the audience, his compact, milky body vibrating with rage until the horribly inevitable explosions. He also spends most of the play semiclothed — forced to undress and redress, gathering up his clothes as he is pushed from brothel to bar, sitting in his underwear with one sock on, or standing naked from the waist down. He is, quite literally, a man laid bare, the trappings of control and civilisation undone as easily as a zip. His potato-like build, starch-coloured face and narrow mouth all play their part in portraying this grey, half-formed man reacting to his worst instincts, a mass of nerves, all trouble spots and flash points.

Mamet makes much of race in the play — the most shocking thing about it is still Edmond’s barrage of racial insults as he attacks the black pimp — but it is more as a way of dealing with the wider implications of human nature than through any campaigning zeal. By showing unleashed racism, the playwright indicates the impotence of bigotry and the inherent weakness and fear it betrays. “Every fear is a wish,” says Edmond, as the final scenes flirt uncertainly with redemption. This might be an abridged version of the long, dark night of the soul, but it remains complex, tense and memorably visceral. It is human nature, red in eye, tooth and claw — an insistent, disturbing vision to take with you into the city night outside.

John Peter is away