NBC is toiling to bring back the notorious "Twenty-One"--the game show that brought down the genre in the late '50s and shook the entire broadcast television industry.

NBC executives did not attempt to hide their envy of ABC's hit quiz show "Who Wants to Be a Millionaire?" when they leaked news of their "Twenty-One" plans to the trade papers yesterday. NBC owns the broadcast rights to the most famous quiz show in TV history, which was the focus of Robert Redford's 1994 movie "Quiz Show."

"Twenty-One" debuted on the network in the fall of 1956; Columbia University English professor Charles Van Doren became a national celebrity after snagging $129,000 on the program--the largest single sum ever presented on a TV quiz show at that time--and NBC made him a regular feature on its "Today" show. But when a contestant defeated by Van Doren cried foul, a New York grand jury investigated, leading to a 1959 congressional probe. Van Doren became the star witness, saying he had been given answers to questions and that even his eventual defeat on the show had been scripted.

So why would NBC want to bring back the show that has come to symbolize the industry's greatest shame? That's easy--when "Twenty-One" was canceled in 1958, it was still being watched in about 27 percent of all U.S. TV homes (in those days, the technology was not in place to tabulate how many actual viewers were watching).

For comparison, "Friends," the No. 1 show of Premiere Week last week, averaged only about 18 percent of American TV homes. And the best "ER" has ever done is to snare 29 percent.

In fact, execs at NBC are looking at the show's tawdry past as a plus.

"I think the notoriety of it and the danger work in our favor," says NBC Senior VP Rick Ludwin, who's working on reviving the project.

"It's an intriguing property and we will certainly have a small army of compliance and [broadcast standards and] practices people watching our every move. Who would want to be the broadcast standards person who allowed the most notorious show in the history of television back on the air and had something go wrong? I'm sure it will be carefully monitored."

Ludwin also does not think NBC will have any trouble finding a host for the program. "I think you may be surprised by the people willing to do this," he said.

Look out, late-night laffers. Starting Friday, Ted Koppel will present a five-part "Nightline" series examining how an unidentified U.S. city would handle a biological weapons attack.

"Biowar" will be played out in real time in the late-night time slot. On Friday, "Nightline" will "report" that terrorists have released anthrax spores into a subway system during rush hour.

The program, as usual, won't air over the weekend, and the terrorist attack and government response are apparently deferring to "Monday Night Football" because "Biowar" takes Monday off as well. Part 2 airs Tuesday, and by the last edition, next Friday, the death toll will be at nearly 50,000, a criminal investigation will be underway and basic services will be provided by the military.

Koppel worked closely with Kyle Olsen on the project; he's an authority on chemical and biological weapons and the program manager for Research Planning Inc., which has been designing and conducting chemical and biological terrorism response exercises for cities across the country. He's interviewed during each broadcast. And following each "Biowar" report, Koppel will conduct a panel discussion with Atlanta Mayor Bill Campbell, Philly police commissioner John Timoney, New York City Office of Emergency Management Director Jerome Hauer and the acting epidemiologist for Texas, Dennis Perrotta.

NBC has ordered a full season's worth of episodes on drama series "Third Watch" and "Law & Order: Special Victims Unit"--after seeing numbers on just one episode of each show.

Both did well in their debuts last week. "SVU," the "Law & Order" spinoff, snared 14.1 million viewers on Monday at 9 p.m.--NBC's best premiere for a new Monday series since 1990. The premiere of "Third Watch" did even better, averaging 20.5 million viewers.

But wait a minute. "Third Watch" premiered in "ER's" cushy Thursday 10 p.m. time slot and I'm pretty sure you could debut a test pattern there and get a Top 20 show out of it. Shouldn't NBC have waited to see how "Third Watch" fared in its regular Sunday time period before ordering nine more episodes at about $2.5 million a pop?

And where's that full-season pickup on "The West Wing"? NBC's new White House drama bagged 17 million viewers, airing in its regular Wednesday 9 p.m. time period--the largest audience NBC has seen since '92 for a premiere in that prime-time spot. But NBC didn't announce any pickup on that show. What gives?

A network spokeswoman says the two dramas were picked up this quickly because the network has more finished episodes on each and and both shows tested well with focus groups.

"We debuted seven shows this past week and each will be evaluated and decisions will be made," the spokeswoman said. "We can't pick them all up at once."

Efforts to contact a programming executive at NBC who could address this inequity came to naught yesterday. But an NBC insider says it has to do with deadlines written into each show's contract that stipulate when the network must decide whether to pick up the "back nine" episodes, as they're called in the business. If that's the case, and the networks now have to decide whether to pick up a show after seeing numbers on just one episode, I'd say the studios have the better deal-brokers.

"SVU" and "Third Watch" premiered last week with an initial order of 13 episodes. What the network has ordered are nine additional episodes, bringing each drama series's order to a total of 22 episodes. This is called a full-season order, even though the "official" TV season lasts 35 1/2 weeks--leaving room for lots of those "encore presentations," as NBC calls its reruns.

ABC's WJLA (Channel 7) has hired Don Hudson to be morning co-anchor of its new pre-dawn newscast with Carol Costello. Hudson, who has been the main evening anchor at NBC affiliate KRIS in Corpus Christi, Tex., is set to start at WJLA on Oct. 4. Next month Channel 7 begins stretching its local very-early-morning news block to start at 5. NBC's Channel 4 already has launched its competitor to WUSA's cow-milking newscast. Until last month, WUSA (Channel 9) had this field all to itself.

Hudson will also report for other Channel 7 newscasts.

CAPTION: Charles Van Doren testifying in 1959 about the faked "Twenty-One."