Broadway, by George Abbott and Philip Dunning; directed by Gerald Gutierrez; choreographed by Theodore Pappas; set design by John Lee Beatty; costumes by John David Rich; lighting design by David F. Segal.

With Lisa Banes, Suzanne Costallos, Janet DeMay, Harriel Harris, Laura Hicks, J. Michael Butler, John Greenleaf, Matthew Kimbrough, Robert Lovitz, William McGlinn, Randle/Mell, Richard Ooms, Tom Robbins, Charles Shaw-Robinson, Scott Walters and Claudia Wilkens.

At the Terrace Theater through Saturday.

If our criminal justice authorities ever decide to follow the lead of some of their foreign brethren and take a deeper interest in the performing arts, they should begin by clamping down on deceptive first acts.

In some countries, the director and cast of "Broadway" would be jailed. Don't they know that when a first act is as stiff and stilted and slow as the one that launched last night's performance at the Terrace Theater, the second and third acts are expected to stick to the game plan? When a play has been given up for dead at the one-third mark, it isn't kosher to suddenly start treating it with care and affection and pizazz. And it certainly isn't right to tack on a crackerjack song-and-dance curtain call that has every toe in the house itching to join the festivities.

The first sign that something is amiss with "Broadway" comes moments after the opening curtain, when the stage is taken over by chorus girls and gangsters. This is the 1920s, see, so chorus girls are to be expected. But these particular specimens seem to have gotten their accents and gestures from a catalogue, after looking up "chorus girls" and "gangsters" in the table of contents.

Generally speaking, in an entertainment of this kind, the hero and heroine are a trifle bland -- nice people, mind you, but not the couple you'd most like to be locked in an elevator with. We endure their billing and cooing politely, but all the while we're looking forward to the entrance of the colorful secondary characters -- those brassy chorus girls and tough-talking gangsters, for example.

In "Broadway," things are turned topsy turvy. The scenes between Tom Robbins, as a vain but virtuous song-and-dance man, and Harriet Harris, as the dancer he hopes to fold into his act, have a charm and crackle that tend to disappear when Robbins and Harris do -- at least up until that first-act curtain.

As the play proceeds, however, the sincerity of the principals spreads to the supporting players, most of whom demonstrate, sooner or later, that it is possible to play a role extravagantly without sacrificing all conviction.

"Broadway" first opened on Broadway in the season of 1926-27. It was the joint work of Philip Dunning and the American theater's most noteworthy nonagenarian, George Abbot.

Some theatergoers may wonder about the lasting appeal of a half-century old backstage melodrama that has managed to achieve and retain a convincing obscurity through the succeeding decades. Bringing back the '20s, after all, has become big business in the '70s. The absolute bottom of the barrel may not have been scraped yet, but the mucky mid-levels certainly have been.

So "Broadway" comes as a happy surprise -- a rich pastry filled with simple cliches and spiked with intoxicating insouciance. For sure, the hero and heroine are the spitting image of a few hundred other backstage couples -- he pining away while she falls under the shady influence of an underworld figure. But they conduct themselves with a certain low-keyed freshness. "When you see me coming, he asks, "doesn't your heart beat faster?" "Yeah, sure," she concedes. "Well," he says, "that's what they call love at first sight."

And when the hero finally takes his stand against the gangster, it is with the line, "I wouldn't stay here and entertain you guys if you were to kiss my foot in Macy's window." Performed here by the Acting Company, "Broadway" will run for three weeks at the Kennedy Center.