Theatre: Speak the speech, I pray you

Antony and Cleopatra

Olivier, SE1

Amadeus

Old Vic, SE1

Real Classy Affair

Royal Court Upstairs, WC2

The new , with Helen Mirren and Alan Rickman, is tough to follow. Across 10 years and two continents, we struggle on: at moments of high emotion, or when the set is on the move, or actors have to face upstage, or yet another relative clause sneaks in before the end of a speech, the consonants vanish, and we are left with empty vowels. It sets the mind racing - mainly backwards. Sorry, you think, what was that they just said?

The National's dream team of Mirren and Rickman has delivered the punters (sold out before previews), but not the goods. The techniques of stage and screen look very distinct. A master of the close-up, voice-over and reaction shot, Rickman is stumped in the Olivier; unable to find the energy to spin iambic pentameters in front of 1,000 people. His nasal slur rises and falls mainly in volume. I had one of the best seats in the Olivier. I had just read the play. And I was looking for the surtitles.

Some of them can do it; as Enobarbus, Antony's right-hand man, Finbar Lynch hangs on tight to his consonants. The best verse speaker in the company, this wiry, cranial figure is brisk and ironic. Thanks to him, we know how Antony met Cleopatra, and what qualities she possesses. Lynch is joined, most of the time, by Samuel West's prissy, pallid Octavius. He can spell out Antony's exploits in Modena, and list, across seven lines, without a fluff, the names of Antony's new allies.

Mirren's mercurial Cleopatra swings between the two. Sometimes, turning on a sixpence between emotions, she can be hilariously precise at portraying the actressy queen. But when losing her rag with messengers, she slips across and joins the music makers. Only in the candlelit last act, as she prepares for her death, does her statuesque directness win us over.

Early on, director Sean Mathias spreads out rugs, cushions, courtiers and silver plates stacked with fruit. Only isn't a feast for the eyes. Its richness lies in its reported speech. The cast has to lead us into the verse, so that we can share in the gossip and flashbacks.

With 40 scenes, the changes ought to have been swift. Tim Hatley's earthen wall of slats slides monotonously up and down. The one element that's always audible is the clanking music in the scene changes. Actors stand and wait for the set to stop moving and the music to end. Awful.

One actor with the authority to move between small screen and big stage is David Suchet. He seizes the massive role of the 18th-century Viennese Salieri in Amadeus with supreme technical skill. He gives the impression he's simply narrating, yet the range, colour and pitch of his narration is magnificently varied. As the text demands, Suchet is as "sleek as a cat", and the frozen feline exterior presents an immaculate asexuality. It is a good contrast to Michael Sheen's tousle-haired, toothy, randy Mozart. Their pairing alone justifies Peter Hall's handsome revival.

Not having seen Amadeus for nearly 20 years it's a surprise to discover exactly the same moments setting my spine tingling. These have little to do with the composer Salieri's relationship with God - "We are enemies, you and I." Nor is it the shock value of Sheen's unbuttoned Mozart - excellent, though he is - running around doing fart jokes and jumping on top of Lucy Wybrow's Constanze. Nor the mystery of Mozart's death and whether or not Salieri had a hand in it.

The grit in the piece, which ironically isn't its big theme, is wonderfully simple. One professional describes the impact of listening to another's work. Suchet's Salieri hears, off-stage, the bassoons and basset horns in Mozart's latest piece: "Suddenly, high above it, sounded a single note on the oboe. It hung there unwavering - piercing me through." Salieri's awe and horror makes non-musicians hear it in a new way.

If it were a biography, Amadeus would make a travesty of Mozart, but this is a fable about mediocrity facing up to sublime talent. When you think how tricky it is to introduce either God or Mozart - let alone Mozart's music - into a play, then Shaffer's achievement in fashioning successful middle-brow entertainment out of all three is extraordinary.

Last week the National announced its list of the 100 most "significant" plays this century. An alternative list might be the most significant scripts that didn't originate in the theatre: screenwriters Paul Schrader, Robert Towne and Quentin Tarantino have been as influential in the theatre as any contemporary playwright.

In Nick Grosso's Real Classy Affair, half of which is set in a north London pub, a bunch of strutting, shiny-suited guys order pints and shorts, and trade their loopy idiomatic brand of pub philosophy; what they "fink" about "fings". The rhythmic phrasing, repetitions and periphrastic tone ("what warrants this fleetin' call?") is straight out of a gangster movie. Either that, or young men in north London pubs get it from the movies - and plays just have to reflect that.

Halfway through the second act, James Macdonald's stylish production goes for broke. The cast sits round a table that's littered with glasses. Someone puts Rod Stewart on the juke box, and, as the set revolves, they sink deeper and deeper into their thoughts. It's pure freewheeling drama. Are we going to watch them listening to the entire track? We are. The scene doesn't quite hold: there's not enough subtext. But it's typical of this bravura piece that it has a go.

Real Classy Affair has a basic plot: several guys after one girl. So Grosso's comedy of manners switches between the pub and a flat where the elfin Liza Walker (the waif from Closer) irons a mountain of white shirts. Joseph Fiennes is mesmeric as Billy: nodding his deep-set eyes, stroking his jaw with his fingertips, and suggesting more than a dash of Jonathan Pryce. Nick Moran is comically impervious as Walker's husband, not even noticing when she dyes her hair pink. If Real Classy Affair cut 15 minutes from its second act it could make some handy money.

Still harping on about the National, spare a thought for the people who built it. In Exodus, director Jatinder Verma's latest for Tara Arts, we follow the Asians who fled Kenya in 1968 as a result of the Africanisation programme and Commonwealth Immigration Bill. The abrupt shift from Nairobi to London is wittily evoked by a cast of six, performing in a large mogul tent. In Kenya, many Asians had been employed building the railway. One of the insights into their chilly new life in England was that some found work building the venue for this week's .

'': Olivier, SE1 (0171 452 3000), to 3 December; 'Amadeus': Old Vic, SE1 (0171 494 5494), to 16 January; 'Real Classy Affair': Royal Court Upstairs, WC2 (0171 565 5000), to 14 November; 'Exodus': BAC, SW11 (0171 223 2223) to 1 November.