IT IS AFTER midnight on a rainy Boston night in the fall. A small group of tired men sit in the living room of one of the nicer Ritz Carlton suites. They are smoking (cigars and cigarettes, but no pipes); they are sweating; and, if it is very late, they may be screaming at each other.

These men are nervous and upset and tired because they are "on the road" with a Broadway show. They have just read the first editions of the next day's papers, and they have found that Kevin Kelly (drama critic of the Globe) and Eliot Norton (of the Record American) do not like the show they have written. These men sitting around a littered coffee table know that if--when their work opens in New York a month later--Clive Barnes (of the New York Times) does not like their show, they are in big trouble. Their show will close, their artistic reputations will suffer, and the play's investors will lose a lot of money ($150,000 and up for a drama, $500,000 and up for a musical). Indeed, the stakes are high.

Yet, as anyone who has been involved with a Broadway show during the past 40-odd years will tell you, this is all part of the game. Producers send a show on the road (usually to Boston, Philadelphia, Washington, New Haven or any combination of two or three of them) so that the out-of-town critics can point out the mistakes that have to be corrected before the production faces the New York critics. But if the flaws pointed out by the provincial critics are major, fixing a show on the road becomes a hectic, often panicky, race against time.

IN MID-NOVEMBER just such a show opened at the Colonial Theatre in Boston. The show, Dear World, had all the earmarks of a hit: a hot star (Angela Lansbury); a composer-lyricist who had never written for a flop (Jerry Herman, whose previous efforts included Hello Dolly and Mame); and a successful librettist team (Jerome Lawrence and Robert E. Lee, authors of Mame and Inherit the Wind). Dear World's five-week tryout engagement here was a virtual sellout before the opening night.

Unfortunately, the biggest advance sale in the world is no insurance against mediocre audience and critical response. In Dear World's case, the opening night audience at the Colonial was polite, but little more. The show's jokes got the mildest of laughs; the musical numbers merited only perfunctory applause. Much later, when the cast and creators were back in their hotel rooms, the reviews confirmed the audience reaction. Kelly said major revisions were in order, and Norton, usually enthusiastic about Broadways musicals and standard comedies, had only faint praise for Dear World.

The very next day, the show's producer and authors started to rewrite the show, practically from scratch. Within a week, the director, Peter Glenville, had been replaced (by Joe Layton). Within a month, a whole new first act was on stage. This is no small job, considering the complexities of putting together a Broadway musical.

As each new scene is written, it is passed on to the actors, who must learn their new lines in about 24 hours. As the new lines are learned, the scenes are put into rehearsal during the day. Meanwhile, the actors play the old show at night, knowing that what they are performing will be out of the show as soon as the new material is ready to go in.

Besides the new dialogue, there are the new songs, the new dances, and, for Dear World, the new sets. Not only must each new song be composed and learned by the performers, but it must be orchestrated, copied into parts, and rehearsed by the orchestra. Joe Layton, the new director, also took over the job of choreographer, thereby necessitating the removal of all the dancing devised by the show's original choreographer, Donald Saddler. So, Layton had to divide his limited time between rehearsing the actors and the dancers. He also had to wait for the new sets to be designed, built in New York and shipped to Boston.

NEEDLESS TO SAY, everybody works to the point of exhaustion. Often, in the most desperate of cases, a producer will bring in additional writers to "doctor" or, hopefully, save the show. Alexander Cohen, Dear World's producer, used his wife, Hildy Parks, and another librettist, Joe Masteroff (who wrote Cabaret) to fix up his production. Neither of these show doctors will receive program credit for their work, but they will get a flat sum of money, and, if their rewriting is substantial, perhaps a percentage royalty.

The producer and director will also make cast changes. Some actors will lose their jobs because their roles no longer exist in the new version; others will be fired and replaced. By its fourth Boston week, Dear World had lost about a half-dozen of its original performers.

It's a mess, all right, but does it do any good? Dear World's new first act, even though substantially different from the original, got just as bad, if not worse, audience reaction. The critics had criticized the musical's shortchanging of the serious aspects of the play from which it had been adapted, Jean Giraudoux's Mad-woman of Chaillot. Apparently the authors took this prevalent criticism so seriously that they decided to drown the first act with eerie, sur-realistic doom. The audience was bored and dumbfounded, particularly considering the fact that the unchanged second act had a light, humorous tone.

NOW Dear World seemed to be past the point of no return. The doubtful new act cost in the neighborhood of $200,000 to put in (on top of the original outlay of $600,000), and the second act had not yet been touched. The show was scheduled to open in New York on Dec. 26, or about two weeks after the Boston closing.

Realizing that his show -- now the most expensive in Broadway history--would be a sure flop unless more radical changes could be made, producer Cohen decided to postpone the opening indefinitely, with all performances in New York designated as "previews" until he considered Dear World ready for an opening before critics. While critics accept this practice of previews as an addition to the road tryout period, they could not abide by Cohen's plan to play the unfinished show into the distant future before paying audiences. Several of the first-nighters threatened to show up at the show unannounced one night and write reviews for the next morning. To head this off, Cohen finally set the premiere date--last night, a full three months after the Boston opening--and, by now, Dear World's fate has been decided. It has had more previews than any show in recent history, with the possible exceptions of last year's Golden Rainbow (a Steve Lawrence-Eydie Gorme vehicle) and the 1963 Hot Spot (Judy Holliday's last show). Both of these shows were critical and financial flops.

Sometimes, however, a show's future looks sufficiently ominous for the producer to close it before its official opening. One of the most legendary examples is David Merrick's musical Breakfast at Tiffany's. That one changed its title as well as directors and writers on the road. Originally written by screenwriter Nunnally Johnson, the musical's book was turned over to Abe Burrows and, eventually, Edward Albee. After six hellish weeks in Boston and Philadelphia Tiffany's played four previews in New York before Merrick closed it at a personal loss of $650,000.

A show can even close on the road before reaching Broadway in any form. Last year, Merrick's Mata Hari (which cost as much as Tiffany's) folded in Washington shortly after a disastrous benefit - premiere during which scenery collapsed and the leading lady was caught nude on stage in a costume change. Merrick evidently found the show unfixable, sent director Vincente Minelli back to California, and auctioned off the sets to to Washington University play-houses.