Simon Russell Beale is King Lear King Lear Oliver Theatre, National January 23 2014

There has not, since 2007, been a National Theatre production of a Shakespearean play anything like as engaging, thrilling and involving as the Sam Mendes helmed revival of King Lear now playing in the Olivier Theatre. Certainly, never before has an audience collectively held their breath or gazed in uniform wonder at the work of the Bard in that space as they often do here.

In no small measure, this is a direct result of the cinematic approach to the staging and the remarkably evocative set and costumes from the genius that is Andrew Ward and the particularly effective use of light and darkness courtesy of Paul Pyant. This is one of those almost modern dress productions, with roots firmly in the World Wars of the Twentieth Century, but it works splendidly. The whole of the Olivier's vast stage is utilised, and there are impressive epic scenes as well as moments of quiet intimacy. It's a wonderful imagining of this quite difficult tragedy.

Most impressive of all is the directness of the story-telling and the rich, acutely detailed characterisations given to the main players. This is no standard Lear - it is a unique and refreshingly even-handed ensemble approach. And by far the best casting at the National in a very long time.

Some of the beauty of the poetic language is lost - well, quite a lot really - but despite that, there is so much commitment here, so much depth to the portrayals, so much sureness about the story-telling that, unusually, it does not matter quite so much.

There are many wonderful moments that will be seared on the memory: Lear's ruthless division of his kingdom, delivered with Lear's face hidden from the audience, increasing the power and venom of the key moments; the entrance of Regan and Goneril, silently but perfectly establishing these vile siblings; the first appearance of the clerk-like Edmund and his transformation into the almost superman Nazi traitor; the quiet but mesmerising look on Regan's face as her husband, her sister and her brother-in-law debate tactics; the Fool's face when he and Lear are atop the mountain facing the elements; the first, wild, stark naked appearance of the deranged Edgar (Poor Tom); the delicious impersonation of Regan by the Fool; the unexpected and shockingly brutal murder of the Fool by the mad Lear; the look on Lear's face when he sees his bloody handiwork; the vicious and horrific blinding of Gloucester with a corkscrew (complete with popping eye-ball); the unveiling of Cordelia and the French army; the tender reunion of blind Gloucester and revived Edgar; Lear's anguished howls as he enters carrying Cordelia's corpse and his slow, perfect descent to death; Edgar's final delicate prayer.

Mendes has a clear vision for King Lear and delivers the goods. The direction is sprightly, intelligent and illuminating. The first Act, at about two hours, literally flys by. In terms of overall presentation and staging, this is a very impressive and glorious production - streets ahead of anything Lord Hytner has presided over.

The very best performance comes from Stephen Boxer, who is quite magnificent as Gloucester. He reaches every high note, of drama, of truth, of poetic delivery. He is spellbinding to watch. Faultless.

Anna Maxwell-Martin is deliciously Dynasty as the power-crazy Regan. Her dress, her hair, her smoking, her air, her sense of innate superiority, her wide open vicious eyes, her childish rants, her extraordinary work at the funeral of her husband: she is an unrelenting source of joy and revulsion. And she died splendidly. Her orgasmic reaction to Gloucester's blinding was startling but perfectly in tune with her detailed, intense performance.

Tom Brooke is wonderful as Edgar, lost, remote and easily deceived; then as Poor Tom he is superb, managing the feat of walking the tightrope of almost insanity. His restoration at the finale is sumptuously satisfying. Unexpectedly, Brooke is quite superb in every way.

Kate Fleetwood is the personification of female steel as Goneril. Tightly coiled and coiffed, she is resplendently hideous, treachery etched on every pore. The only scene where she, Regan and Cordelia talk together is frighteningly real, dripping with venomous contempt.

As the bastard Edmund, Sam Troughton does the best stage work of his career. Like Hitler, he morphs from petty clerk to powerful maniac and is responsible for many deaths and deceits along the way. He is a fiery and blustery villain - but his best moments are the very quiet ones.

I have never seen Stanley Townsend better than he is here as the wronged Kent. He is excellent in every way and his deep, mellifluous voice adds a welcome texture to proceedings.

Michael Nardone is impressive, in Etonian entitled thug mode as the Duke of Cornwall. He works well with Maxwell Smith and his work with the corkscrew both before and during Gloucester's savage blinding is immaculate. The same, however, can not be said for Richard Clothier, who is intensely dull and ineffectual as the Duke of Albany. His is the one unbelievable character in the mix and his command of the text shockingly inadequate.

Olivia Vinall starts badly as Cordelia - too much shouting and far too little warmth - but comes into her own in Act Two. Her rallying of support for her hunted father is genuine and touching, and her post-death scenes would not have worked as well but for the empathy she built with the audience.

The Fool is a difficult role to pull off but Adrian Scarborough manages to be both funny and touching, observant and witty, insightful and roguish. It's a quite delicious mix. And it works extremely well. When the Fool dies at Lear's hands, you know that the descent into Hell has begun. In a very palpable way, Lear kills an essential part of his own self.

Ross Waiton makes a significant impression as first the King of France and then the Captain in the final scenes.

Then there is Simon Russell Beale's Lear.

Never has either the opening scene, where the ageing King capriciously divides his kingdom and thereby draws deep enemy lines between his daughters, or the final scene, where Lear's life ebbs away following his harrowing delivery of the body of Cordelia to the gathered masses, worked as well as it does here. The brutal display of unhinged power leads inexorably to the unhinged moment of release, his one loyal and truly loved child having died. At these two extremes, Simon Russell Beale excels.

In the middle, however, all is not quite so rosy. Looking for all the world like he was basing his Lear on Ian Judge ( hair, beard, stance, rage ) but at the same time approaching the early scenes almost as if he were Richard III ( there is the sense of a hunch on his back, an oddly held hand, a strange gait ) Beale is mercurial and often fascinating and compelling. But he delivers the text at break-neck speed always, except for the final scene, and this detracts from the overall effect. The famous storm soliloquy does not reach the operatic and resonant heights it should. He finds the humour, but occasionally to the cost of the drama and the sense of tragedy.

Beale approaches the part cerebrally rather than personally or with volcanic self- righteousness. While Derek Jacobi may have been a better Lear in the Grandage Donmar production (he never lost sight of the vocal work) Beale's is certainly a cleverly concerned and executed interpretation. Occasionally, his work is fragile and beautiful, shattering even. He speaks with alacrity but with precise, almost chiselled diction. Sometimes, though, more passion is required, more intensity of disbelieving confusion, more grandeur born of rank.

This is an efficient and technically focussed performance of Lear. But the capricious decisions, all of which cost the character dearly, are observed rather than felt by Beale.

That said, I have never seen a better final scene than this: his entrance with the corpse of Cordelia is nothing short of miraculous in its capacity to sway opinion and to reflect hard, soul-destroying grief.

The stage is awash with silent watchful young men who play various soldiers. The numbers are impressive, the mood smouldering, resentful and volatile as allegiances sway. Mendes is right to fill the stage with these supernumeraries: they give the tragedy a real sense of cause-and-effect, and the royal machinations reverberate through the Kingdom.

What is most memorable about Mendes' vision here is how this play, so often just seen as a vehicle for a star turn in the titular role becomes a dark meditation on the way fathers impact upon the lives of their children. Here, the stories of Gloucester and Lear are told in clear parallel, with each man being as important as the other: both have children, both reject one, both make mistakes about which child to expect support from, both are betrayed by their offspring and both are responsible for the death of their own. This approach makes the play both more intimate and more universal, and certainly more remarkable.

Mendes has delivered a night of Shakespeare that is worthwhile and fulfilling in almost every way. And with more playing, Beale's Lear will, no doubt, become more coherent, more lyrical and more devastating. But for the moment, Stephen Boxer's star is the shining light in this sumptuous theatrical delight.