Theatre: No one cares, dey jez keeps singin'

SNATCHES OF famous tunes bob up and down in the overture, townspeople crowd round the steamboat, Cotton Blossom, women gathering up their skirts, and men tipping their hats, and as we sink into the seductive mix of nostalgia and liberal sentiment that is Show Boat, waves of goodwill stir inside, inspiring warm, kindly, charitable thoughts. Then it hits me - the roast turkey, the brandy butter, the paper hats! Can you flop in front of this stuff without having had your Christmas dinner first?

The American musical is the one art form that could dislodge Dickens as patron saint of the modern Christmas. And Show Boat is its daddy. Jerome Kern and Oscar Hammerstein II took Edna Ferber's 1926 epic about theatre folk on the Mississippi and made it the first musical with the plot, songs and subject-matter to withstand a revival today. In theatre, "epic" is a code word for shows in which we don't care deeply about any one individual because there are too darn many of them. Time plays a big role instead. By the second act, daughters are the age their mums were in the first act, and guys are dousing their hair with talcum powder. Men never go bald in epics, they go a shade of grey.

It's a love story of sorts. At the end of the first act there is a duet between Cap'n Andy's daughter Magnolia and the cheap river gambler Gaylord Ravenal. The lovers tell each other that "you're the prize that heaven has sent", and "here's a bright and beautiful world". But the dramatic release is mild. We've already seen that the big affair in this show, the heavy necking that's taking place on a dark river beneath a starry sky, is between the authors and popular theatre itself.

No one is better suited to do epic theatre or a show about showbiz than 70-year-old New York director Hal Prince. His production of Show Boat opened in Toronto when he was a mere slip of man - back in 1993 - and arrives in London with five Tony awards. We certainly aren't getting the second 11, or - with a cast this size - the second 70. This revival has prestige stamped all over it. Prince is a master at handling crowds, and seamlessly staging and shaping scenes through lighting. Every moment carries extra details - figures in the background polish rails, dust carpets and sweep the floor. There can't be a single dust mite flourishing on the Cotton Blossom. Susan Stroman's choreography brings a scurry and attack to the smallest movements. And the cast is strong. Yet when you get home you wonder to whom exactly you are meant to recommend it.

Show Boat peaks within the first half hour and that high point is a tremendous low. When Michel Bell delivers his first line as Joe, a single "yeah", you think a tube train must be passing underneath. For "Ol' Man River" he sits, his head sunk into a V-neck of sweat on his shirt, staring at the floor, as if perplexed by the source of this rumble. It's an electrifying performance. There are whales out there in the Atlantic sending him back replies.

We leave the Mississippi when Magnolia and Ravenal quit the Cotton Blossom and head to Chicago. The years keep rolling along, this time in street scenes, as Prince presents new costumes, musical fads and headlines in a montage of US history. As more and more people sweep out of the elegant Palmer Hotel on to the pavement outside we wait for the liveried doorman to sing an anthem to dose ol' revolvin' doors:

Dey jez keeps spinnin',

Dey jez keeps spinnin' aroun'.

With a cast this size, you've no idea in which order they'll take their bow at the curtain call. Especially when the central character is that complex figure, part-loveable, part-loathsome, American Society. George Grizzard pulls it all together as the tolerant Cap'n Andy, and Joel Blum does funny walks and vaudeville tricks as the travelling actor, Schulz. Both are a delight. But the hero of the night remains Jerome Kern. Not many shows leave you with half a dozen numbers to hum on the way home.

Driving up the A40 for a new play by Stephen Poliakoff, I saw that the B4632 out of Stratford leads to a place called Broadway - not much chance of heading down that road, I was thinking, with Talk of the City, an extensively researched play about BBC radio in the 1930s - and then, 10 minutes into Poliakoff's latest, Broadway didn't seem such a wild idea. Certainly, if it were a track on a CD, you'd immediately want to rewind and play the first scene again.

Someone's reading the news on air, scantily clad showgirls gather in an art-deco studio, a man in evening dress cues in the band, the lead singer arrives in a ball gown, the character actor takes his position, the news ends, and they go into the opening medley of "Friday Night at Eight". It's a delicious mix of showbiz brio, BBC professionalism, theatrical artifice, period detail and mystery. Poliakoff captures a sublime world where propriety ensures no word is spoken that hasn't been scripted, and a careful eye is kept on the intonation. In this ironic portrayal of early broadcasting, Poliakoff finds numerous contemporary parallels. We see how hard it is to modernise an institution, how administrators love to regulate, how resistant the public is to change, and - the play's main theme - the difficulty in getting people to take any interest in events that happen "abroad". No small matter, then as now.

The BBC executive, who's played with a lovely period earnestness and intellectual hauteur by Angus Wright is superbly matched by David Westhead's bright, egotistical song-and-dance man. They team up to try and broadcast a story about the treatment of Jews in Germany. As Poliakoff's play develops, it floats free from the detailed observations that make the early scenes so funny and plausible. The size of the themes, and the consequences of the actions taken by the characters, begin to overwhelm the stage action. Never mind: Talk of the City is still a funny, serious and intriguingly apposite play that says as much about Britain today as Britain in the 1930s. Recommended.

If life is complicated, trying to end it can be more so. You buy a shotgun, drive off a cliff, or grab a bottle of pills. Even if you have a 100 barbiturates, though, there's the problem of swallowing them. Take them too fast and you throw up. Take them too slow and you pass out. The trick - as we discover in the most riveting scene in David Rabe's new play, A Question of Mercy - is to establish a rhythm, a count of one, two, three, taking tiny, tiny sips each time, so that you drink as little water as possible.

A Question of Mercy is adapted from an essay by Connecticut surgeon Dr Richard Seltzer which was based on a true incident. A man with full-blown Aids is sure he wants to die. His friends want to help him but they don't want to end up in jail. The nuances involved are complex. When he's taking the pills, they could stay in the room with him and watch, or sit next door, or go for a walk, or see a movie. In which case the question becomes, "which movie do you see?"

A Question of Mercy is a one-issue play, but an anecdotal one, that cleverly shifts the focus on to the people who'll be left behind. The only person who knows what he wants is the man with Aids. Everyone else squirms with indecision. This ambivalence forces them to disentangle their confused attitudes. Rabe pursues the quandaries with a forensic eye, and his nervy, fractured dialogue ideally suits their embarrassment, frustration and efforts at self-denial. Imagine a team of bank-robbers having to plan a job while having serious ethical qualms about stealing. The American cast from Long Wharf, New Haven, are good, with an outstanding performance from David Chandler as the harried, grim-faced surgeon - hunched shoulders, hands plunged into his pockets - blocking any sloppy thinking like a bouncer at a nightclub.

'Show Boat': Prince Edward, W1 (0171 447 5400), to 17 Oct. 'The Talk of the City': RSC Stratford Swan (01789 295623), in rep to Sept. 'A Question of Mercy': Bush, W12 (0181 743 3388), to 23 May.