When the opening titles roll for Sunday's edition of the long-running PBS series "Mystery!," the black-and-white Edward Gorey figures will be enlivened with a few touches of red, white and blue. This marks a change at the nation's public broadcasting network, a shift from the old reliance on British-produced fare to homegrown stuff. No tea parties and toffs with twee accents; tonight's two-hour episode, based on a Tony Hillerman novel, is produced by Robert Redford and takes place on an Indian reservation in the American Southwest.

Welcome to Pat Mitchell's PBS.

Since taking over as CEO of the network in March 2000, Mitchell has been herding cats, struggling to bring unity and stability to the nation's loose affiliation of 349 noncommercial television stations. With varying success, she has shifted some of the network's "icon" series from their hallowed time slots in an effort to bring a new thematic consistency to the weekly offerings: history on Mondays, science on Tuesdays, culture on Wednesdays. Old series, like "Mystery!," are being revamped; new series, like "Frontier House" (which borrows a page from the commercial networks' passion for reality TV), have been introduced. Even PBS's promotional spots and tag lines are being remade. "Be more . . ." has replaced "Stay curious" as the network's motto.

None of these changes, even ones that seem superficial, have been easy. The major hurdles are, and always have been, financial. Under an FCC mandate, PBS must begin digital broadcasting by May 1. The new technology, which the network estimates will cost $1.7 billion, will allow it to broadcast in high-definition, and potentially offer more channels and more interactive programming. Those costs are hitting stations at the same time that the economy is in a slump and political leaders at the local, state and federal levels are looking for ways to economize. Many of the large corporations that have been increasingly important to the network since new guidelines allowing "enhanced" underwriting (more time to sell their message on air) aren't feeling flush, either.

Purrs and Hisses

On her desk, Mitchell keeps a picture of a cat walking nervously in front of a phalanx of German shepherds. She offers it as a metaphor for her job.

"People say, wouldn't it be easier if this were just a network and you could tell everybody what to do," she says. "Easier, yes; better, no. Not necessarily."

Throw a dart at the map, call the head of the closest PBS station, and the first thing you hear is sympathy for Mitchell and her impossible job. They call her gutsy and innovative, and then they pounce. "American Family," a new drama that focuses on Hispanic family life, isn't doing well in one Midwest market where there isn't a sizable Hispanic audience. "Life 360," a freewheeling show that took an edgier look at broad themes in American life, never broke through entrenched resistance to new shows. "American High," a series that looked at the lives of American teenagers, doesn't make sense for the PBS audience. "That's just not an age range we're ever going to attract," says one station executive.

Earlier this month, on the eve of a weekend trip to Sundance, Utah, to attend an advance screening of the new Redford project, Mitchell was happy to celebrate the symbolic achievement of introducing an American writer, Hillerman, to PBS audiences. "Skinwalkers," the first of four Hillerman mysteries coming to PBS, is a small accomplishment compared with what needs to be done, but even small accomplishments resound at a network that has a reputation for evolving at a molasses pace.

"I think we turned a corner in the fall," Mitchell says, sitting in her office on the sixth floor of PBS headquarters, just south of Reagan National Airport in Arlington. There's a black-and-white photograph of the Dalai Lama on the wall, and it's inscribed by the photographer to "Pat." There are also several shelves of Emmy statues and Peabody Awards, relics of 30 formidable years in broadcasting. Still fresh in the mid-afternoon, despite a day that began in Upstate New York with a 5 a.m. flight (she spends much of her life on the road, visiting stations and teaching), she's formidable herself.

Mitchell, 59, began her career as an educator, teaching English and drama at the University of Georgia. She was an accidental, but zealous, convert to journalism, beginning as a writer and researcher with Look magazine. By 1972, at the age of 29, she had her first television job, at WBZ-TV in Boston. She dates her first serious exposure to public television from those years, when she pitched in at another station, the powerhouse PBS affiliate WGBH, during pledge drives.

"When I was running my own little independent company and struggling to produce documentaries, I looked at PBS as a model," she remembers. Even so, she spent much of her career in commercial television, producing hundreds of hours of documentaries for Ted Turner's TBS and CNN after leaving her own independent company, VU, in 1992. Among them was the 24-hour series "Cold War."

"Ted Turner had shared that with me before it was out, and I found it terrific," says Ken Burns, the independent filmmaker whose work is a mainstay of PBS's glamour offerings. "As with a good deal of Turner's productions, there was this initial courageousness in tackling the subject. And it was smartly produced, smartly handled, and it didn't go for the cheap and easy."

Mitchell's career as a producer gave her intellectual clout, a raft of awards (she produced two documentaries nominated for Academy Awards) and very good industry contacts. She sits on the board of Redford's Sundance Institute, and it is thanks to her Redford connection that Tony Hillerman's novels will finally be made into films.

For more than 14 years, Redford had been sitting on the rights to Hillerman's novels, hoping to produce a series of films that focused more on the mystery writer's endearing Native American characters than on the usual glitz of big-budget fare. He had in mind the old Charlie Chan mysteries, relatively inexpensive films with the possibility of a cult following. But even Redford couldn't sell the idea, not to a mainstream studio, nor to his own Sundance Channel.

"Hillerman is popular with the public," Redford says from Utah. "But the risk doesn't go to the public, it goes to the corporate people, and there is a gap between what the public wants to see and what the corporate people are willing to make."

Enter Pat Mitchell, who proposed bringing the project to PBS. She was attracted by the American subject, and the Native American setting. Diversity is still a respectable word at PBS.

The moral of the story, says Redford, is that PBS isn't just a noncommercial alternative to commercial television. It's a noncommercial alternative to American society, especially the entertainment industry, which, he believes, has lost sight of what disenfranchised viewers want: alternatives.

The Center of Attention

PBS is a network built on niche audiences, which is both its major strength and its Achilles' heel. Over and over at PBS central, one hears the term "new media landscape," by which network executives mean a world of ever-expanding entertainment choices, hundreds of channels that cater to ever more thinly sliced niche curiosities and demographics, and an as-yet-unclear future of digital television that may further atomize the old core audience. Although cable television made PBS much more accessible (viewers no longer had to fiddle with rabbit ears to find a UHF signal), it also whittled away at PBS's audience of refugees from the inanity of mainstream network television.

For better and worse, PBS is also a network identified with two demographics that the commercial world treats almost with contempt: the very young and the older, educated viewer. With rare exceptions, it is the only place where serious public affairs programming shares space with the high arts and independent filmmaking. At the same time, it's hard to base an identity on being everything that everyone else isn't. Lesli Rotenberg, the network's senior vice president for brand management and strategic positioning, has a job as difficult as her title is unwieldy: make PBS look more like real television without losing sight of its mission.

"Bring in new viewers, project an image that is welcoming, [yet] not alienate the core and preserve what's best about the brand," she explains.

The challenge of bringing cohesion to the network, with the identifiable feel and tempo that the commercial networks establish, invites far-flung comparisons. Burns says Mitchell's job is like being Jefferson Davis running the Confederacy when you need Abraham Lincoln's federal powers.

Doug Myrland, general manager of KPBS-TV in San Diego, compares it to selling cars.

"We're like a Ford dealer," he says. "We're a franchise. We're dependent on PBS for the core product, and like a Ford dealer, we want them to come out with great new models. Something that will bring people back. But talk to any Ford dealer and they have criticisms of the new model. My customers want leather, and you're not offering leather. But ultimately, you can't have 350 Ford dealers designing the new Explorer."

Mitchell is keenly sensitive to the independent streak of her constituent stations. The mantra is: The community stations are our best asset. They also pay the bills. In 1967, Congress created the Corporation for Public Broadcasting, which this year has a $350 million federal appropriation. It distributes federal money to PBS stations; they, in turn, pay dues to PBS, which produces programming. PBS, which has about 500 employees and a $318 million budget, also receives federal money directly, both from CPB and the Department of Education.

The relationship between Arlington and the affiliates has had its ups and downs, and Mitchell has seen a couple of the downs already. Under pressure from PBS central, Maryland Public Television dumped Louis Rukeyser as host of "Wall Street Week." The goal, very much in line with Mitchell's agenda to refresh the icon programs, was a new look and a new feel to the long-running money program; instead, Rukeyser moved over to commercial cable, took his underwriters with him, and left MPT with the makings of a serious budget shortfall. Decisions in Arlington can have unforeseen, even disastrous consequences for the affiliates, especially the ones that produce PBS programming.

In October, at a conference of station development directors held in Dallas, Mitchell raised the delicate issue of pledge breaks and their increasing presence on local stations.

Some stations, she said, were asking for pledges nearly 100 days a year and had reached a point of diminishing returns. "As pledge weeks have looked more and more like Shop at Home, or promotional videos for self-help gurus, viewers are left to wonder whether they're buying a product or supporting a valuable public service," she said.

PBS viewers might have said, "Amen, sister," but that was not her audience. She was addressing the people charged with finding the money to pay the local bills, and they know things are getting increasingly difficult.

Though pledge revenue has been rising, the total number of pledges is decreasing, even though on-air pledge time has gone up 78 percent over the past 10 years. The result is that public television is becoming dependent on a smaller number of viewers and, though no one says it openly at PBS, those viewers are the traditionalist "core audience." That, in turn, makes it ever more difficult to make programming changes at PBS central.

Political Realities

The stresses on PBS are not just internal. Follow the money, or the lack of it, and you find the fissures that threaten the system from the outside. Ten years ago, PBS was on the hit list of organizations like the Heritage Foundation, which argued that the system wasn't sufficiently accountable to taxpayers, that cable television's niche programming was making PBS irrelevant and that "enhanced underwriting" was stealing money from the commercial networks. The network found itself attacked from the left and the right, the former arguing that it was too beholden to its corporate donors and the latter incensed when it ran programs deemed "anti-family," such as the highly acclaimed "Tales of the City," which dramatized gay life in San Francisco.

Today, says Wayne Godwin, Mitchell's chief operating officer, the network has weathered the political tempests. Maybe.

No one wants to speculate about what will happen with the changes brought by the recent election, but the last time the Republican Party was feeling its oats in Congress, it talked up cutting PBS out of the budget.

So far, PBS executives project calm, but there have been some ominous rumblings. When Bill Moyers used his commentary on a recent installment of "Now With Bill Moyers" to lament the results of the election, it got Bill O'Reilly at Fox News boiling. But a week and a half after the vote, Mitchell shrugs it off. One show does not a network make is PBS's usual line of defense when hit with charges of bias.

"I don't take 'The O'Reilly Factor' and say, 'That's Fox,' " says Mitchell.

A little bit of noise on Fox News can reverberate very widely for PBS, yet, curiously, O'Reilly's network does about half the prime-time numbers that PBS does and is available to fewer households. The perception that PBS is somehow irrelevant probably has more to do with the kinds of people who watch, and the way they make their political and cultural feelings known.

"Nobody on public television is screaming and yelling at you or their guest for the sake of theater," says Godwin. Despite an average of more than 2 million viewers in prime time, it is an audience that lacks the screamers and yellers who might give it more presence on the cultural scene. Even if it is a low-key presence compared with commercial broadcasting, Mitchell insists it is a force.

"I had a really good career on the other side, and I don't want to seem unduly critical of the commercial world," she says. "But, in fact, I'm very worried about what is going on there. The consolidation of power, the fact that in the years ahead there could be only three or four gatekeepers. In a world with 'Survivor' and 'Fear Factor' -- okay, fine -- but that can't be all we have. Someone has to take chances and serve across diverse populations."

Mitchell is a convincing idealist. She talks about what a relief it is to arrive at work and not start the day by scrutinizing the overnight ratings numbers. She remembers how, in her commercial days, the word "educational" was anathema when attached to a project proposal. She fantasizes about the British Broadcasting System, with its multibillion-dollar state subsidy, and the opportunities for great journalism and drama that kind of money affords the system. But ultimately she's running a network of small parts in a world that likes big numbers.

If numbers were everything, she argues, the network would never have produced documentaries on Osama bin Laden (before 9/11) or the history of Islam.

"You can't just suddenly be a good journalist," says Mitchell. "You have to do it all the time. That's the argument for supporting investigative journalism and serious history even when it isn't popular."

Mitchell's observation about the importance of doing solid work, even when it doesn't garner wide attention, suggests a larger conclusion: That it is easier to shrink the nonprofit sector than it is to regrow it when needed. Her larger task, to maintain PBS's relevance as a leader in that sector, could, in fact, be very easy. Politicians could take their shots without threatening to pull the plug on funding; corporations could demand less overt advertising for the money they give; and individual viewers could give more money and forgo the tote bag.

But that would all depend on a societal commitment to maintaining a public forum on television. Fundamentally, her job is to convince Americans that they need one.

"Tony Hillerman is an extremely popular writer, and yet they thought it wasn't mainstream enough," she says. "Which makes my argument why you need a public broadcasting system."

Since taking over at PBS in 2000, Pat Mitchell has been introducing new series and revamping old ones in an effort to expand the network's audience while trying to keep its 349 noncommercial stations happy.Under Pat Mitchell, PBS has added reality-based "Frontier House," above, and the drama "American Family," left, which focuses on Hispanic family life, to its lineup, but not without complaints from station executives more used to programs like "Now With Bill Moyers," above left, which debuted in January.PBS moves "Mystery!" to the American Southwest on Sunday with "Skinwalkers," starring Adam Beach, left, and Wes Studi.