TONIGHT, just after 9 o'clock, NBC viewers will hear a TV announcer say, "Next! Betrayal and remembrance in the continuing saga of love, and life, in 'Morningside.' " But no one will ever see "Morningside" because suddenly regular programming will be interrupted and an anchorwoman will appear on the screen. She will say, "This is Susan Myles in New York. There is a rapidly unfolding situation in Charleston, S.C, this morning, where an unidentified group is holding four hostages on a ship. Apparently they are demanding to make a statement, live, over the RBS network . . ."

Clairvoyance is not required to predict any of this--only a copy of the script of "Special Bulletin" by Marshall Herskovitz, who produced, with partner Edward Zwick (also the director) an innovative, ambitious and crisply gripping TV drama of that name, the NBC Sunday Night Movie at 9 on Channel 4. Herskovitz and Zwick, with executive producer Don Ohlmeyer, tell a fictional story of nuclear terrorism--a story grimly eerie in its timeliness--as if it were actually unfolding on live TV news. Viewers at home will see the event from precisely the viewpoint they would see it if it were real, through the eyes, technology and prosaic cliche's of television news.

Naturally such an experiment calls to mind the Orson Welles Mercury Theatre broadcast of 1938, "War of the Worlds," when the same technique of staging a bogus newscast sent some radio listeners into conniption fits. They headed for the hills "with towels over their heads," Welles recalled later, thinking the Martians had landed. This event was itself re-created in a TV movie called "The Night that Panicked America."

Zwick and Herskovitz say they don't want to panic America--just shake it up a little and expose it to some extremely clever and entertaining media commentary. But their bombshell detonated right under them last week, when NBC suddenly began getting very, very jumpy about the broadcast and decided to add more and more disclaimers to it, so many as to incense those who made the program and even threaten to withdraw it from the air--a development more unlikely, it should be noted, than anything in the drama itself.

Zwick and Herskovitz submitted their idea to NBC, through Ohlmeyer, a year ago and over ensuing months got it approved by the entertainment division, which as a matter of course ran it by the network censor. The censor ruled that the taped program must be preceded by a disclaimer alerting viewers to the ruse and also interrupted with such disclaimers during the broadcast. There's something weirdly whimsical about the wording of the disclaimers. They tell viewers, "None of what you are seeing is actually happening."

Some people feel that way about whatever they see on television.

Zwick, Herskovitz and Ohlmeyer accepted the need for disclaimers. Then, last week, NBC News executives got a look at the program and went the corporate equivalent of stark raving mad. Although an NBC News adviser had been observing the project all along, NBC News executives panicked at the sight of the final product because they didn't expect it to be as effective as it is.

Whatever else one may say about "Special Bulletin"--and its doomsday scenario does seem a trifle shaky, even considering the high loony population of the world and the resourcefulness of the deranged--it is a shrewd, keen, wise, hip, occasionally lacerating and sometimes gravely funny dark parody of network TV news coverage. Two days of terrorist standoff are telescoped into the two-hour show. Within a few hours of the inception of the crisis, the fictitious network news department has decorated its reports on the story with a title, a logo, animated graphics and a razzle-dazzle musical theme. Yes, it's time for "Flashpoint: America Under Siege."

The two RBS news anchors, Ed Flanders as a Frank Reynolds type ("Somebody get me some information, damn it!" he explodes) and Kathryn Walker as a Jessica Savitch type, have to listen on the air to one of the terrorists lambast them about the way networks cover such events, even though one of the terrorist demands is access to the American people through a live RBS hookup. "I mean, media is just show business, right?" the terrorist scowls into the camera. "Don't you have agents or whatever, like actors do?"

This is the plot: the terrorists toot into Charleston harbor, home of many a nuclear sub, aboard a tugboat called the Liberty May. They take hostages and demand the live hookup before they will release them. Once on the air, they announce they have with them on the tugboat a nuclear device that will be exploded unless the detonating modules from the 960 nuclear warheads in the Charleston area are brought to them.

"Special Bulletin" is not a tract on behalf of a nuclear freeze, thank heaven, though some viewers, already so disposed, will surely take it that way. And it is more than a practical joke, a jumping out and saying of "boo." When Zwick and Herskovitz visited Washington just prior to production, Herskovitz said, "This is not a Halloween prank like Orson Welles did. That's not the point." The point is to tell a story on TV using TV's own reality vocabulary. Zwick and Herskovitz say they wanted to do a drama dealing with nuclear issues long before talk of nuclear freeze became a vogue, if not a veritable blight, and the idea of using TV news techniques is one they had also kicked around. The two came together and--fission. Science fission.

And the result? It works, it works, it works, with a resounding BOOM.

It works so well that NBC executives went wild with terror. And that's what led to the firestorm at NBC corporate headquarters in New York last week. "The problem is, Ohlmeyer did such a terrific job," says M.S. (Bud) Rukeyser Jr., NBC executive vice president. Rukeyser conceded the $2 million project had been in the works for months, and that network executives might look like a bunch of monkeys for their eleventh-hour retreat, but said, "You really have to see the program to understand how there could be confusion. Reading the script wasn't enough. It wasn't until we saw it in its finished form that we realized what a big problem we had. We're trying to serve two masters here and come up with a solution that maintains the integrity of the program but is also responsible to our viewers."

As one precaution, the network will forgo the usual news updates seen during the time period so as not to add to confusion about what's really news and what's just pretending to be.

Zwick is furious about the last-minute cold feet by NBC--"just as furious as I could possibly be," he said Thursday after a long talk with NBC Chairman Grant Tinker, who told him the network's position is that "it is better to err on the side of responsibility." Thus, as of that moment, Zwick said, the program would not only include 14 printed disclaimers that appear on the screen around commercial breaks but, in addition, 10 superimposed "dramatization" disclaimers, like those seen in some commercials, during the dramatic body of the show itself.

Rukeyser denied there will be 14 printed disclaimers and said the total will be closer to five. He said the network was also considering changing the background color on the slide "Special Bulletin" seen before and after commercial breaks because the color chosen by the producers happens to be official "NBC blue" and might contribute to confusion.

"We're not interested in scaring anybody," said Zwick, "but all these disclaimers are going to mitigate some of the impact of the way we're trying to tell this story." Zwick said the program aired in Calgary, Canada, earlier in the week "without a peep" of alarm nor with any Condians running wild through the countryside with towels over their heads. Zwick said he thinks the news department at NBC is reacting with "ludicrous overkill" because they don't like the way their oh-so-noble profession is portrayed in the program. "What they're essentially saying to us is, 'You have done a piece that's very strong,' and then they've taken all these steps to mitigate it and water it down and make it like all other television. But when we set out to do this, we wanted to do something that wasn't like all other television. That's the point."

The drama, shot on tape at actual locations in Charleston in late January and early February--with the full cooperation of Charleston city officials, the producers say--is not so much about nuclear terrorism (although the Washington Monument incident took place just prior to production and was incorporated into a rewrite of the script) as it is about the way media and terrorists try to exploit each other. Both Zwick and Herskovitz, who previously worked on the much-praised ABC series "Family," are concerned with the way network news turns such stories into star-studded shows, replete with catchy titles ("America Held Hostage," to cite a real one) and snappy patter. "You know," said Herskovitz, "we're all sort of inured to the way they package these things. They package disaster."

What Herskovitz and Zwick have done is take the docudrama one step further, either toward perfection or toward sheer madness. Their simulated nuclear crisis is not particularly credible in "Special Bulletin," but the way it's told is bull's-eye. That is, the content is weak but the form is more than willing. Zwick and Herskovitz have flooded it with criminally authenticating details, from the way correspondents interrupt each other as the story breaks, to missed cues and picture break-ups, to hastily composed and file-photo-filled biographies of the terrorists (a zany grab-bag of misfits and psychotics who include a Patty Hearsty rich girl called "Diane Silverman" and the proverbial very-angry black feminist poet, played by Rosalind Cash). If NBC News president Reuven Frank and executive vice president Tom Pettit hate the show--and Pettit has been particularly vociferous on the subject within network ranks--it may be partly because network news has been aped so cleverly and accurately by a couple of guys from Hollywood, and also perhaps because the producers and their craftsmen came up with a better set for their anchors than NBC has been able to do over the years in umpty-ump expensive attempts.

At times, the unfolding story in "Special Bulletin" comes across as ludicrous, but then one has to think, how much more ludicrous is it than some of the actual news events of the past 15 years or so, and the way television has honed its way of covering them? It's a process that deserves scrutiny not just in poker-faced journals and ivory tower think tanks but on television. Praiseworthy trailblazers like the ABC News late night "Viewpoint" broadcasts have done this one way. "Special Bulletin" does it in another way--not a better one, perhaps, but in one more accessible to greater numbers of viewers.

Undoubtedly, some people will tune in at some moment between disclaimers and for a few seconds or minutes could be caught off guard. But then, as Herskovitz says, "There are a lot of people who still think Robert Young is a doctor." Tonight's edition of "Special Bulletin" is a perceptive and persuasive look at the way television colors our perceptions and persuasions, and if all the fuss over it last week draws more viewers to it than normally would tune in, so much the better.