In the first few minutes of the new television show 'Nikita,' a masked bank robber shoots a witness. A suspect takes down a couple of police officers, and a trained killer in a skimpy red bikini breaks a mobster's neck with her bare hands.

What viewers won't see are shopping sprees, moneyed teenagers or flirty scenes with cute guys.

The show reflects new thinking among television networkexecutives: Their core audience -- female viewers -- want to see a woman take down the enemy, preferably with a little bloodshed along the way. The approach overturns years of belief that violent shows turn off women who prefer to watch earnest nurses, headstrong housewives or quirky career women.

Viewers who grew up with video games and Angelina Jolie action movies are driving the types of shows networks will debut this month and redefining how the classic TV heroine is portrayed. On Sept. 9 the CW network will debut 'Nikita,' about a rogue assassin, played by Maggie Q. In the coming weeks NBC will premiere 'Chase' about U.S. Marshal Annie Frost and 'Undercovers' about a husband-and-wife spy team. In July USA introduced 'Covert Affairs' about a 28-year-old CIA trainee who speaks six languages.

Ever since TV began as a way to sell detergent to housewives, networks have tried to stay in tune with changing preferences among women, who watch more TV than men. Female characters evolved from June Cleaver to Murphy Brown and Ally McBeal.

The networks need to refresh their lineup of dramas for women as several big shows are aging. In the season that ended in May, 12.5 million viewers watched 'Desperate Housewives' each week down from 23.4 million in 2004. 'Grey's Anatomy' and 'Gossip Girl' have also declined in popularity, Nielsen says.

That's prompted networks to dig deeper into the femalepsyche. Last spring, the CW network, known for such soapy female-targeted shows as 'Gossip Girl' and '90210,' which follow the trials of privileged youth in Manhattan and Beverly Hills, respectively, commissioned a nation-wide study into what women in their 20s and 30s want. More than 60% of the network's viewers are women, mostly between the ages 18 to 34.

Market researchers asked groups of 10 to 12 women gathered at local coffee shops or a friend's house as well as in traditional focus groups in New York, Los Angeles, Chicago, Atlanta, and Denver to make collages of magazine images they liked. They chose Jennifer Aniston paddle boarding over actresses lying on the beach in bikinis. They preferred absinthe and beer to wine or fruity pink cocktails and gravitated to toned athletes in fitness magazines over models in evening gowns.

They also thought men had gotten wimpier and associated the opposite sex with the bumbling losers played by Jonah Hill and Seth Rogen in recent romantic comedies. 'It was obvious that these women feel like they have to take charge and be the hero,' says Jane Buckingham, president of Trendera, the market research and trend forecasting firm that conducted the study.

Action shows are hard to pull off, and any overly brutal scenes that could be perceived as gratuitous will turn off female viewers, networkexecutives say. There's also a kitsch factor to worry about. TV works with much smaller budgets than movies. With viewers accustomed to seeing slick, expensive stunts and computer-generated enhancements, anything less can look campy.

'In TV you need to shade it so you see the human aspect,' says Matt Corman, an executiveproducer of 'Covert Affairs.' In that show, CIA trainee Annie Walker narrowly escapes certain death when a nearby informant is killed, and then goes to a dinner party at her sister's house. Such moments make viewers okay with action in their living rooms each week, he says. 'You never saw James Bond file a tax return.'

In 'Undercovers,' special agent Samantha Bloom runs a Los Angeles catering business, when she's not chasing down Russian arms dealers in exotic locales. 'It's less superhero-y and more, 'Oh my God,' I can relate to this person and now she's beating the hell out of someone,' says executiveproducer Josh Reims.

To create a drama about U.S. Marshals, writer Jennifer Johnson says she thought about her 4-year-old daughter. Even though her daughter is too young to watch, she wanted to create role models for young women and decided to make the lead a Texas-based Marshal named Annie Frost. Played by petite blonde Kelli Giddish, Frost wears blue jeans and cowboy boots and takes down fugitives twice her size.

'She's such a kick a-- character,' Ms. Giddish said, on a break from shooting on location in Dallas in 100 degree heat. She had recently completed a stunt (with no double) that involved jumping onto the wing of a moving crop duster.

Network executives regularlycommission market research to find out what types of characters viewers like or dislike. They'll often come up with one character type one season -- and something completely different the next.

TV has experimented with action heroines in the past with shows like 'Buffy the Vampire Slayer' and 'Alias,' but those shows largely avoided anything too gritty. 'Nikita' executiveproducer Craig Silverstein says he was hesitant when TV studio Warner Bros. asked him to re-imagine 'Nikita,' inspired by the French film 'La Femme Nikita' which also spawned U.S. movie 'Point of No Return' and a 1997 series on the USA network.