A campaign for a chain of fitness centers is raising eyebrows — and perhaps pulse rates — with a sexy take on the traditional finale to fairy tales.

The campaign, which began this month, promotes the Equinox Fitness Club chain by promising patrons they can achieve their “happily ever.”

“What’s your after?” asks the campaign, the first work for Equinox from its new agency, Fallon Worldwide in Minneapolis, part of the Publicis Groupe. The campaign retains a theme that appeared in previous ads for Equinox, which had been created internally: “It’s not fitness. It’s life.”

To turn up the heat, the campaign is photographed by the fashion photographer Ellen von Unwerth, who has shots ads for brands like Chanel, Diesel, Guess, Tommy Hilfigerand Victoria’s Secret. She presents images that are provocative as well as playful, meant to illustrate themes like inner beauty and fantasy.

These are the sensual situations, some erotic, some voyeuristic, all featuring scads of well-toned skin:

¶Nuns in an art class sketch a hunky naked model who resembles Michelangelo’s David.

¶A buff hottie chooses a naturally fit woman over her rivals, who have opted for cosmetic surgery and too much makeup.

¶A lithe young man bends over backward, literally, to please the guests at a costume party, by serving as their table.

¶A beautiful older woman in full “cougar” mode celebrates her birthday, surrounded by men of various ages who are vying for her attention.

The campaign, with a budget for 2008 estimated at $3 million to $5 million, includes print and outdoor advertisements, posters at the 41 Equinox fitness clubs and a lavish commercial that will appear in movie theaters and online, which demonstrates how yoga classes at Equinox helped Table Boy — actually, a model named Josh Pence — achieve his flexibility.

There are also plans for a redesign of the Equinox Web site (equinoxfitness.com), to be carried out by Organic, a digital agency owned by the Omnicom Group.

Equinox has long been known for campaigns that celebrated the fit human form, presenting gorgeous models of both sexes in as little clothing as possible. And it is not surprising to find a marketer that owns fitness centers using sex to sell memberships.

Still, the campaign is already drawing attention for the frank approach of some of the ads, which can cut both ways.

It can benefit Equinox to stand out in the category of health clubs, which is crowded with competitors that include Bally Total Fitness, David Barton Gym, Crunch Fitness, Curves Fitness Center, Gold’s Gym, L.A. Fitness, New York Sports Club, 24 Hour Fitness and the old-school standbys of the Y.M.C.A. and Y.W.C.A.

Cutting through the clutter is particularly important in January, when the desire to woo consumers thinking of dieting, getting more fit and other New Year’s resolutions leads fitness marketers to flood the media with pitches.

But a campaign that gets noticed because it is deemed too contentious or inappropriate can backfire, especially when a membership at a fitness center is a big-ticket purchase that is rarely made on a whim.

“We knew it would be a little controversial,” says Bianca Kosoy, creative director at Equinox in New York, which is owned by the Related Companies.

“You’re never going to please everyone,” she adds. “What works in New York and Los Angeles is not always well received in San Francisco and Chicago.”

Equinox has clubs in all those locations, along with markets like Boston; Coral Gables, Fla.; Darien, Conn.; and Newport Beach, Calif., and is scheduled to open in cities that include Manhattan Beach, Calif., and Vienna, Va.

To mitigate the severity of any complaints about the campaign, Ms. Kosoy says, “we liked shooting it through the lens of a female photographer.”

Indeed, according to Hillary Benjamin, senior marketing director at Equinox, Ms. Von Unwerth “is known for making women feel beautiful about themselves.”

Her work is “sexy,” Ms. Benjamin says, “but respects the female sex.”

(As for the idea of the men in the ads being treated as sex objects, well, perhaps turnabout is fair play.)

Ms. Benjamin and Ms. Kosoy say they believe the campaign will be appreciated by the Equinox target audience, which Ms. Benjamin describes as well-educated professionals, ages 25 to 55, with high household incomes.

“We call them lifeaholics,” she says. “The one thing that ties them all together is their approach to life: intense, passionate, results-driven, collectors of all things new, who know first about the coolest band or the latest restaurant.”

During the process last summer to find a new agency, Fallon demonstrated it “knew who our consumer is,” Ms. Benjamin says, and also delivered the “big creative idea” that she and Ms. Kosoy was seeking.

Equinox chose Fallon last September over two other New York agencies, Droga5 and Toy.

“The campaign comes from the insight that there’s a deeper reason people work out than to get into shape,” says Eric Sorensen, a copywriter and group creative director at Fallon who developed the campaign with Hans Hansen, an art director and group creative director.

“We all have this idealized fantasy, this endgame, we’re working toward when we go to the gym,” Mr. Sorensen says. “It’s fun to imagine these ‘happily ever afters’ at their most provocative and extreme.”

“Each ad hits on a different theme,” he adds, “because everyone has a different ‘happily ever after.’ ”

As for the idea that some fairy-tale finales may be more Kinsey than Grimm, Equinox is “not afraid to stir the pot, if you will,” Mr. Sorensen says.

That dovetails with the company’s goal of “taking a different approach to fitness,” he adds, by stressing “the life benefit of working out” rather than the short-term results (as appealing as they may be).

All the situations in the ads “are grounded in reality,” Mr. Sorensen says, “but pushed.”

For instance, the attractive older woman at the birthday party “wants to maintain her youth,” he adds, while the Adonis being sketched by the nuns is comfortable enough with his “godlike body” to — as Gunilla Knutson used to say in the Noxema shaving cream commercials — take it off, take it all off.

The print ads are appearing in newspapers like The Los Angeles Times, The New York Post and The New York Times as well as in the regional and national editions of magazines like Esquire, US Weekly, Vanity Fair and Vogue.

The print outlets are being selected for what Ms. Benjamin calls their “editorial focus on social currency” — that is, they cover subjects that the target audience talks, gossips and buzzes about.

The campaign is intended to run beyond this year, Ms. Kosoy says, and will be refreshed with additional ads.

“There are so many ‘happily evers’ out there,” she adds, and the intent will be to “interpret them in smart, unexpected ways.”

Perhaps one future ad will depict a class of muscular nude models sketching a nun.