IT WAS a freak hit. A lively off-Broadway show that had lots of energy and tunes but was frankly a bit of a mess. In the end the lack of stagecraft was irrelevant. Rent hit the front pages when Jonathan Larson, its 35-year-old lyricist and composer, died after the dress rehearsal. The story then wrote itself. Here was a struggling artist who had written a musical about struggling artists. Here was the future, cruelly snatched away. In no time the show was a smash hit. It transferred to Broadway and last week opened in the West End.

In Puccini's La Boheme, from which Larson's rock opera draws its plot, Rudolph is a poet in a garret and Mimi is the consumptive seamstress who comes downstairs because her candle has blown out. In Rent, things are more complicated. Roger is a guitarist who is an HIV-positive former heroin addict. Mimi is a dancer in a S&M bar who is HIV-positive and a heroin addict. And so on.

You could say Rent is a Nineties musical for the Generation X-ers with a raucous soundtrack, industrial designs and Brechtian techniques. You'd want to qualify that: it's an early Nineties musical that has taken four years to reach our shores. (Sensations travel slowly these days. ) It's not new. It has the accoutrements of newness - the exotic and grungey costumes, the mix of styles, from rap to gospel to tango, and lots of Manhattan references. What it sells is an ambience that says: this is now. Or this was now when it was written.

When I saw it in New York, I wondered whether London audiences would pick up half the references. That isn't a problem. London audiences can't hear half the references. Rent pulls off a technical feat: it manages to be loud and inaudible.

The vision these Nineties bohemians share is tunnel vision. Here they are, a performance artist, a video film-maker, a songwriter, a dancer - artists, that is, who might take an interest in the world beyond the Lower East Side loft in which they're squatting. They live in the wealthiest country in the world during an era of unrivalled prosperity. Do they feel lucky? You must be kidding. "Anywhere, after New York," sings one of them in all earnestness, "would be a pleasure cruise." Lucky that Rent wasn't opening in Jakarta. It would take a lot of nerve to deliver that line.

The narrator, Mark, is a video artist who is, characteristically, making a home movie about his friends. In this solipsistic world, parents are comic figures wittering into your voicemail, children and babies simply don't exist, and rent is something that gets in the way of your integrity as an artist. There's just Roger and Mark and Mimi. As they put it, succinctly enough: "There's only us, there's only now." In Rent, we have moved beyond the "Me" generation and entered the "Mimi" generation. Rent has been hyped as the future. Deep down, there's nothing here that couldn't have been written by our old Broadway colleagues, Ersatz and Schmaltz.

The triple bill of plays by Harold Pinter at the Donmar brings together two TV plays written in the early 1960s with A Kind of Alaska, inspired by Oliver Sacks's book, Awakenings, written in the early 1980s. The last play comes first. It's the best.

In A Kind of Alaska, Penelope Wilton plays Deborah, the 45-year-old woman whose body has aged while her mind has stayed that of the 16-year-old who contracted encephalitis lethargica, or sleeping sickness. Her eyes flit round, her mind jumps about, she digests news then ignores it, with a startling freshness. As the doctor, Bill Nighy has a marvellous stillness - as if languor and tautness had found a equilibrium. Only the twitch of an eyebrow, the clasping of his hands or the way he keeps formulating answers to questions then stopping himself from replying suggests the enormous tension.

The play contains moments of profound shock. One comes when Nighy tells the uncomprehending Wilton that she's been asleep for 29 years. Another comes when Deborah's sister, Pauline (Brid Brennan) walks in. She gleams with welcome reassurance and Wilton looks totally mystified. With a perfect sense of control, Karel Reisz directs as tense and emotional a 55 minutes as you could imagine.

The main attraction of The Collection, a play about infidelity between two couples - a husband and wife and two men - is that Pinter himself is it it. He's very funny, crossing the stage with sturdy gracelessness and demanding to know where the grapefruit juice is with a speedy testiness. His wobbly crease of a smile disturbs us more than other people's sternest frowns. Douglas Hodge is on top form as the husband who thinks he's been cheated on, grinning through his threats with oafish buoyancy. The evening tails off slightly with The Lover, where surprise is built into the action as much as suspense. For once, Pinter's characters follow a tight, premeditated plotline. Director Joe Harmston allows Lia Williams and Hodge too much freedom.

Watching these three plays you wonder, in a chicken-and-egg way, which came first - Pinter's dramatic instinct or his subject matter. The sexual tensions, power games, questions and answers, the withholding of information and the circling round particular words are the stuff of pure theatre. But they are also his subject.

It's not often that a play deals with those in the business world who make the British undisputed world leaders in their field (second only to the Americans), who provide real jobs, prop up the economy and maintain our standard of living. It's not often you see a play about the people who make and distribute lethal weapons.

At the Piccadilly Theatre there's one that says big business pushes governments around and rewards compliant politicians with approving press coverage in the newspapers they own. It says big business donates money to political parties and receives honours in return. It says big business even sponsors the very organisations which are set up to oppose them. All this, and it has a character called "the prince of darkness".

Sandline in Sierra Leone, Bernie Ecclestone and the ban on tobacco sponsorship, Rupert Murdoch dropping in last week at Number 10, and the strange coincidence of Peter Mandelson's nickname: you have to admit, it's pretty nifty work to have produced such a damaging portrait of New Labour just one year on. Only it was back in 1905 that Bernard Shaw wrote Major Barbara.

Peter Hall's inspired revival of Shaw's play has electrifying moments of political savvy. It reminds us forcibly of the parochialism of most new writing. Here is political theatre at its most topical and astute. Major Barbara (played with fresh-faced sincerity by Gemma Redgrave) is a salvation army officer running a mission in West Ham. Her story pales beside the razor-sharp debates between her future husband, the young Greek professor, Adolphus Cusins, and her father, the arms manufacturer, Andrew Undershaft.

We want to speed through the details of the plot - about the family tradition of finding a foundling to inherit the Undershaft munitions, and whether or not Barbara is going to marry Adolphus. The play leaps into life - with superb passages of political rhetoric - when Undershaft persuades Cusins to take over the business.

It was inspired, too, to cast Peter Bowles as the arms manufacturer. He has the debonair smoothness of the boulevard perfomer that would play equally well in the boardroom. He argues with a lethal frankness that's unclouded by conventional moral concerns. Bowles finds a worthy opponent in the boyish, terrier-like professor - the excellent David Yelland - who has the academic's untrammelled sense of his own rightness. Anna Carteret is imperiously dismissive as Lady Undershaft and Crispin Bonham- Carter suitably priggish as the public-school son, standing up for character and a clear sense of right and wrong. It's a fascinating evening: a play written a decade before the First World War makes a corrosively bleak assessment of the relationship between money, power and politics. One that looks uncannily accurate today.

'Rent': Shaftesbury, WC2 (07000 211221). 'Three by Harold Pinter': Donmar, WC2 (0171 369 1732), to 12 Jun; then touring.'Major Barbara': Piccadilly, W1 (0171 369 1734), in rep to Jul.