King Lear, Almeida at King's Cross, London; <br></br>Push Up, Royal Court Upstairs, London; <br></br>Pinter Sketches, National Theatre Lyttelton, London

A deluge so deep even the furniture is afloat

Stormy weather is wreaking havoc inside the award-winning Almeida Theatre. During the central scenes of King Lear – staged by Jonathan Kent with Oliver Ford Davies shouldering the title role – an electrifying tempest rages, meteorologically and psychologically. At first everything looks plush. Set designer Paul Brown has transformed the auditorium into an oak-panelled, palatial chamber where Lear's daughters and aides attend.

Ford Davies strides in and his decision to split up his realm on retirement is announced as a public TV broadcast. Ensconced behind a gold-embossed desk, he has the air of a benign dictator. He chuckles as Suzanne Burden's Goneril and Lizzy McInnerny's Regan step forward with nervous smiles to confirm filial devotion. This Lear seems sadly aware, deep down, that established certainties are about to disintegrate.

When he banishes Nancy Carroll's Cordelia for refusing to tow the line, he shatters his looking glass. And soon after, as morality goes to the dogs and Ford Davies grows mad with grief, his mansion is stunningly rent asunder. Lightning flashes through fissures, walls fall and rain pours on this ruin.

The tiny hovel where Ford Davies – stripped to his underwear – finds Tom Hollander's ragged, ousted Edgar is actually Lear's desk, shoved in a flooded corner. So there's no heath as such, but rather a journey into the King's crazed mind and dark visions of a political scene turning barbaric.

This production intelligently suggests a back story for the degenerates who gain ascendancy. James Frain's outstanding Edmund, before hardening into a villain, is a sweetly smiling youth whose sensitivity is wounded by being introduced as Gloucester's bastard. Burden and McInnerny, flinching as they taunt their father, imply they've been bullied for years. Indeed, Ford Davies – the cuddliest old softie in British theatre – proves a Lear of startling authority and snarling ferocity. The first three Acts tear along impressively – with Shakespeare's iambics driven by intense, naturalistic emotion.

After the interval, regrettably, several key players and the director's sense of momentum go awry. The hurricane ceases, preparing us for healing scenes. But David Ryall's blinded Gloucester mutters his speeches of despair and stoicism as if he's reading the phone directory. Carroll rushes lyrical lines and Ford Davies could quieten some of his on-going rants.

However, his path in and out of madness is otherwise superbly charted and the tenderness of his death scene – when he cradles Cordelia's corpse like a new-born baby – is heartrending. A great performance.

If Lear teaches us, on a royal scale, about relinquishing power without sufficient domestic love, Push Up wants you to laugh at and beware of competitive City types – particularly those without (oh, woe betide) a steady private life. Opening the Court's International Playwrights Season, this office drama by Germany's Roland Schimmelpfennig (smoothly translated by Maja Zade) is set in a multinational corporation's chic HQ.

In three near-identical offices, colleagues battle for supremacy. Sian Thomas's crisp Angelika is jealous of Lucy Whybrow's younger, steely Sabine. According to their asides, each is suppressing sexual frustrations and insecurities. Next, David Tennant and Jaqueline Defferary argue over a promotional ad and, covertly, recall a one-night stand they failed to develop. Thirdly, Robin Soans plays a withered head of department with a threatening protégé (burly Nigel Lindsay) – two more dysfunctional singletons avidly reaching for top posts.

This piece is engrossing as Ramin Gray's fine cast offer hushed performances. But the tension and satire wear thin as Schimmelpfennig's writing is simplistic, schematic and repetitive. Exotic flights of fancy are limited and characters, instead of becoming individuated in their monologues, reprise one another's words. Perhaps they're meant to be soul mates estranged by business dealings (a view familiar from David Mamet). In practice, Schimmelpfennig comes across as a playwright with bad corporate instincts, producing a bunch of clones.

Finally, the National fleetingly staged a handful of old and new Sketches by Harold Pinter, with a cameo appearance by the playwright. Several of these vignettes are hardly Pinter at his best. Still, some are gems and warmer than his longer dramas. In Trouble in the Works (1959), Patrick Marber played hilarious power games as a factory foreman, with Corin Redgrave embodying his flailing boss. Penned in 2000 and performed here for the first time by Penelope Wilton, Tess is a rather flimsy impression of well-bred party chat, though it strikingly recalls Ashes to Ashes, skewing off into a violent fantasy. As for the brand new satire, Press Conference, I've never seen such a unanimously fawning bunch of journalists. But Pinter plays a forcefully nightmarish Police Chief/Culture Minister, smiling as he unveils demented policies. Beyond this, the writer himself is a terribly distressing sight, ravaged by the side effects of chemotherapy. Yet it's some comfort that he is fighting on, with leonine strength, against political corruption as against cancer.

k.bassett@independent.co.uk

'King Lear': Almeida at King's Cross, London N1 (020 7359 4404), to 30 March; 'Push Up': Royal Court, London SW1 (020 7565 5000), to 2 March