Spamalot, Palace Theatre, London <br/> The Cryptogram, Donmar Warehouse, London <br/> Summer and Smoke, Apollo Shaftesbury, London <br/> Krapp's Last Tape, Royal Court Upstairs, London

The Holy Grail of theatreland

God's ginormous cartoon feet come thudding down through the clouds, Terry Gilliam-style, in Spamalot - the hit musical version of Monty Python and the Holy Grail which has just transferred from Broadway to the West End. Tim Curry's pea-brained, tubby King Arthur and his shamelessly silly knights are soon cantering off on their mission to find the sacred vessel. This naturally involves much prancing on the spot accompanied by coconut shells, but that's interspersed here with additional, farcically glitzy fantasies - not least babes in bikinis twirling maces at Camelot and tap routines in the deep, dark forest. Eric Idle and his fellow-composer John Du Prez's loving rip-off of the movie may well become the hottest alternative panto in town this Christmas.

Some gags do drag, the humour being at points more infantile than witty. Moreover, when the plot departs from the screenplay and Arthur's ultimate destination proves to be a stage in the West End, one very New York joke about needing Jews on board falls uncomfortably flat. That should have been reworked for London. But mainly this is a jolly romp for Python lovers and Spamalot is a buoyant burlesque of musical clichés too. Hannah Waddingham's Lady of the Lake is irresistible as a storming jazz diva descending into scatting gibberish, and her slushy love duet, "The song that goes like this", is a joyous deconstruction of Andrew Lloyd Webber's favourite tricks. Not all the Round Table twerps are equally hilarious but Mike Nichols' ensemble exude warm brio. Curry is effortlessly droll, looking like a cross between Trevor Nunn and Humpty Dumpty, and Tom Goodman-Hill is having a ball in a variety of roles, recapturing the punctilious pomposity of John Cleese without limiting himself to a slavish imitation. His taunting French guard on the battlements is flamboyantly preposterous, blowing a long raspberry as his head bobs between the crenellations like a deflating balloon. All in all, the show earns a sizable thumbs-up (if not a ginormous one).

Nearby at the Donmar, the real mystery about David Mamet's The Cryptogram is why director Josie Rourke has revived it. This three-hander only lasts an hour, yet it still manages to be immensely irritating. A small boy called John can't sleep. He keeps on coming downstairs, talking about hearing voices and also asking his mum and her gay (or bisexual?) friend, Del, manic questions about a torn blanket. Apparently, he is excited about accompanying his father on some male-bonding trek into the woods, but then we gather Dad has disappeared after extramarital cheating, lies have been told about Dad and Del's camping, and comforting certainties are shattered.

To give it due credit, Rourke's production creates an atmosphere of edginess, doubt, doom and gloom. Kim Cattrall puts in a fine performance as the elegant 1950s housewife who grows increasingly frantic and directs her wounded rage at her son. This play also feels discernibly, tantalisingly like disguised personal reminiscence. However, the directing misses hints of satiric humour and, too often, the dialogue is mannered and monotonous in pitch, rhythm and volume. Douglas Henshall's Del is sub-operatic, intoning half his lines. In fact, step back and you might think this was a send-up rather than the work of a really top dramatist. Mamet's fractured and circling phrases - which at their best are riveting - are rendered enfuriating here, with the characters' would-be philosophising coming over like portentous lessons fed through a message-scrambler. The Cryptogram exudes mystery but, in practice, is frustratingly insubstantial - or just radically inarticulate.

Adrian Noble's staging of Summer and Smoke, ultimately accrues a more poignant sense of devastation. Tennessee Williams' tragic romance about true love missed is set in the Deep South circa 1916 and revolves around a womanising doctor called John (Chris Carmack) and a neurotic, repressed minister's daughter named Alma (Rosamund Pike). Williams heavy-handedly underlines the contrasting poles in his moral conflict, spelling out that Alma means "Soul" in case anyone hasn't grasped the difference between her and the sensual John. Yet alongside strong narrative symmetries, a touching understated grief pervades their parting. Alma's shaky attempt to woo John back comes too late. Even as her virtuous example saves him from the slippery slope to debauchery, she moves in the opposite direction, hoping to meet him half-way but falling into the arms of strangers. The big snag is Noble's production is far from seductive at first, with ill-painted backdrops and dreadfully stiff blocking. Still, the later scenes in the doctor's surgery, when John's professionalism blurs with his yearning, are passionately charged and this play is certainly worth reviving.

Krapp's Last Tape gains riveting menace and an extraordinary sharp personal edge with Harold Pinter (inset) taking the title role in Samuel Beckett's famous monologue with spools. Hunched over his desk in a sepulchral dark attic, replaying his recorded journals of yesteryear, Pinter's Krapp is not going gently into his final goodnight. He's a haggard, brooding, near-Gothic horror, his eyes in half-shadow glaring into the void with bitter rage - relieved by moments of more luminous recollected tenderness and regret. Staged by Ian Rickson, this is one of the most inspired pieces of star casting I have ever seen. The Court's short run sold out in just 17 minutes, but thankfully Pinter's performance is also being filmed by BBC4 for posterity. On one level, this is his hail and fond farewell to Beckett's masterly spare style which, of course, influenced his own as a young playwright.

This production bypasses some of Beckett's comedy, all the clowning business with bananas having been cut. Yet what a brilliant stroke of dry wit having Pinter, who has famously struggled to write, as Beckett's diarist of increasingly few words, testily flinging his scribbled notes to the floor. And then, of course, there's the agonising closeness to home. The ravages of Pinter's battle with cancer are staring you in the face as he sits wheelchair-bound, and every word he speaks sounds as if it comes from the grave, deep and rasping. The combination of frailty and tenacity is terribly moving. At one point, when the wind rattles the attic's shadowy window, he glances over his shoulder and you feel his mortal fear. At the same time, you sense this man will give Death himself a fierce run for his money when he comes knocking.

k.bassett@independent.co.uk

* 'Spamalot' (0870 895 5579), booking to 26 May; 'The Cryptogram' (0870 060 6624), to 25 Nov; 'Summer and Smoke' (0870 890 1101), to 3 Feb; 'Krapp's Last Tape' (020 7565 5000), to 24 Oct