"When I realized now I could have sex with any guy I wanted," says Nicole, "I was like a kid in a candy store."

I've been wondering what's up. In her early thirties, Nicole (all the names have been changed here, so as to encourage fuller disclosure) is an attractive, athletic woman with blue eyes, lots of freckles, and a mop of curly light-brown hair. But since I last saw her, she has become almost...luminous. Today, as we linger over drinks at the Orbit Room on Market Street, Nicole glows as if she's been on a weeklong juice fast or a beach holiday in Fiji. Since her divorce a year ago, she has devoted her considerable energy mostly to biking and running. But that, apparently, does not account for her newfound radiance.

Nicole lives in the Marina but does not feel that she belongs there. She isn't comfortable among the girls with ironed-straight hair and the former frat boys driving gas-guzzlers, and she shrinks from the bars on Union Street where they meet to make their short- and long-term allainces. So strong is Nicole's distatste for convention that it may have torched her marriage. Her husband wanted kids and a picket fence—every Marina girl's dream, perhaps, but Nicole wasn't ready. In their last year together, the couple made love only once.

After the divorce, a friend told her, "This is a chance for you to be alone and discover yourself." For three months, Nicole stayed home in the evenings, drinking wine alone. Eventually she decided that it wasn't herself she needed to discover. It's men.

"I'm really curious about them," she tells me. There may be other motives to her serial explorations—the fear of getting hurt again, perhaps. But suddenly I find I'm less interested in why she seeks out men than in how.

San Francisco may be a mecca of sexual freedom, but the Marina certainly is not its epicenter. What does liberation look like for a straight girl in a buttoned-down hood who has no interest in marriage or even in a relationship? Where is her Folsom Street, her Castro?

Leave it to the Orbit Room's infamous cocktails to pry loose the answers. After her dismal evenings at home concluded, Nicole tells me, she sought out friends of friends, usually a safe bet. Gradually emboldened, she allowed strangers to chat her up, then to pick her up. She felt like an amateur: the first time it happened, she was so flustered she gave her ex's phone number to a potential date by mistake.

Soon enough there was a guy from her spinning class who asked her out for a drink, which was followed by another spin about the bedroom. There was the international aid worker, so worldly that he made her feel insignificant. That didn't last long. Later, in bed, Nicole marveled that casual sex could be so much fun, and that she could be so good at it.

She moved to the Internet, where she could choose her community norms. On Adult FriendFinder, her friend Laura had met a guy whose oral skills she particularly commended. Nicole got his email address and sent him a note. "He was good-looking in his late twenties, sort of Brad Pitt-looking," she shrugs. "It was nice."

I'm a little surprised. After just a few months of bedroom rambunctionsness, Nicole is already blasé? Surely she's had a sexual education that many women, constrained by social norms, will never have. I beg her to tell me some of what she's learned.

Nicole sips her drink and thinks it over. "I guess my ex was pretty well hung. I didn't appreciate it at the time."

Maybe you learn more from sleeping with the same person a dozen times, I think, than from sleeping once with a dozen different people.

Recently, through Match.com, Nicole met Jack, a corporate type who drives a sports car. Nicole prefers bohemians, or thought she did, and at first Jack struck her as your average suit. But then they kissed and, she says "All of a sudden he was a different person." It was the kind of chemistry that sneaks up on you, that you don't even know is present or possible, until you kiss.

Shortly after they began sleeping together, Jack took her to the theater. By then Nicole had pegged him as a sweet but conventional guy who, by some quirk of fate, had pheromones that interlocked perfectly with hers. Still, the more they talked, the more he surprised her. He was smart and funny, and during the play his hand settled gently on her thigh. A tender gesture, not a sexual one.

Nicole sat there trying to look as if she were used to it. But she'd had so much of being touched the other way, she'd forgotten what this felt like. It was unexpected and sweet, like finding a handwritten letter in the mail.

Former telephone sex worker Helena Echlin pries mercilessly into the private lives of strangers—then tells all. Next: a sex buddly changes genders. You get over it.