There's a pivotal moment in Guys and Dolls, when Clive Rowe, playing one of the gamblers, Nicely-Nicely, belts out the last words of the mock spiritual, "Sit Down, You're Rockin' the Boat", and shifts his hefty figure back to his seat in the Save-a-Soul Mission, just in time for the final chord and a snappy lighting cue. Henry Goodman, who plays Nathan Detroit, the fast-talking fixer of crap games, leaps to his feet to bark out the next line, but the audience won't let him. They want an encore.

Goodman holds his poker face for a few seconds then swings his arm back to cue in the band, and the endearingly innocent Rowe, who looks as if he's been dreamt up by a cartoonist using a thick felt-tip, bundles downstage and delivers an encore. Goodman then leaps to his feet again - but he still can't get his next line out. The audience want a second encore. And then a third. This time, the company give it everything, vocally and choreographically. It is tempting, after that, to demand a fourth encore - purely in the spirit of scientific enquiry, to see if director Richard Eyre and choreographer David Toguri could possibly have found any place else to take this go-for-broke company. But no, Goodman gets his line out and we move on. Still, everything has changed.

With Rowe's show-stopping number, two-thirds of the way through the evening, something special occurs in the Olivier: emotion floods the theatre and only some of it is coming off the stage. No amount of sitting at home and watching TV will deliver a comparable experience. Here is an audience that is actually, almost embarrassingly, in love with a piece of musical theatre, and the euphoria is intoxicating. What happens at this moment is that the show becomes theirs: that shift in ownership defines Guys and Dolls unmistakably as a hit.

Of course, the production itself is one big encore. Richard Eyre first did Guys and Dolls at the National in 1982, so this is a revival of his revival. But if, like me, you didn't see it last time, there is no need to sit around worrying whether the 1996 version is or isn't better than its predecessor. This is about as good as anything you are likely to see.

In the original Damon Runyon stories (superbly adapted by Jo Swerling and Abe Burrows) there's a character, who doesn't appear here, called Ambrose Hammer. He's a critic who gets to see a show every night and considers this a very great hardship. If only Ambrose could have seen what happens when the book for a musical has enough wit and character to be a comedy in its own right. Or if he could have heard what happens when a such a book gets a score by Frank Loesser: one that contains as many hits as half-a-dozen modern blockbuster musicals put together. Ambrose Hammer was always very pessimistic about everything, but he would have to concede - possibly over a sturgeon sandwich in Mindy's - that okay, this time, here was a piece that didn't smell "in nine different keys".

The first round of applause comes with the set. The designer John Gunter creates a nostalgic Times Square with kiosks and neon signs. Eyre's cast fill this stage, from the opening number onwards, with every kind of Broadway tic. The guys wear loud double-breasted suits and trilbies. The dolls totter across the stage in high heels and squeaky voices. The men, in particular, suffer from a condition known as Broadway Spasms. They tug suddenly at their cuffs, tweak the rims of their hats, flick out their arms and jerk their chins. Advanced sufferers do a special kind of exit where they skip in the air, lean back as if on a rocking horse, and shoot offstage. Just when you think this show might be in danger of becoming a tribute to a genre - a touch cute and knowing - the principals take charge, and the rest is one long bath.

We can lie back and relax because the four leads can sing, dance and act (sometimes all three at once). Goodman brings a tremendous energy to the twitchy, fidgety Nathan, driving the show forward as he ducks and weaves, and only occasionally suggests that it's the performance and not the character which is manic. As Adelaide, who has been engaged to Nathan for 14 years, Imelda Staunton switches sublimely between vamping in a nightclub and homely remonstrations with her intended. She puckers up her face, her cheeks twitching at the prospect of a sneeze, and blithely shares her irrefutable logic about her fiance: "I've always thought how wonderful he would be if he was different." Staunton has a lovely gift for keeping an audience absolutely in step with her thought processes. She clenches her fist with inspired delight as she determines that the best thing to do is "Marry the Man Today".

As Sky Masterson, the man who bets Goodman that he can get any girl to lunch with him in Havana, the suavely calm Clarke Peters anchors the show with the unhurried elegance of a crooner in a late-night, smoke-filled cabaret. He's older than Sky ought to be, which suggests, nicely enough, that he might be ripe for a change in life. Joanna Riding captivates as Sarah Brown, the buttoned-up mission worker, who reveals a hilariously raunchy degree of abandonment when the Bacardis take hold in Havana. Riding has a luminous period look and a beautifully clear, dramatic voice. If it's Clive Rowe who brings Guys and Dolls to a standstill in the second act, it's in no small measure due to Peters and Riding having set the audience alight in the first.

At Stratford Adrian Noble directs a penetrating version of Ibsen's late, rarely performed play Little Eyolf (translated by Michael Meyer). Rob Howell's abstract set of an almost bare stage that develops fjord- like fissures positions the play perfectly between its remorseless psychological truths and its stranger symbolism. Strong affecting performances from (among others) Joanne Pearce as the jealous wife Rita, and Robert Glenister as her idealistic husband, ensure the scorching frankness of Little Eyolf scares as much as it moves.

The Bridewell consolidates its reputation for rediscovering neglected musicals with Marry Me a Little, a canny 1980 two-hander that strings together a score of previously unrelated Sondheim songs. A man and a woman each spend a pre-Christmas night alone in their New York apartments, only meeting in each other's imaginations. This 75-minute show, persuasively sung by Rebecca Front and Clive Carter, demonstrates again that Sondheim writes better about the absence of love than its presence.

In last week's review of A Midsummer Night's Dream I strangely mistook Leonard Fenton for Frank Thornton. Apologies to both actors.

Theatre details: Going Out, page 10.