Blake, a fast-rising junior executive at a major movie studio, was sipping champagne in the back of a chartered black SUV en route to a party in the Hills when one of the members of his tipsy cohort—all West Hollywood creative types—pulled out a baggie of off-white powder. Blake (who asked that his real name not be used) gave up coke years ago and now, as an on-and-off vegan who generally sticks to locavore principles, treats his body as a temple. But his friends in the SUV weren't doing key bumps—one by one, they were dipping their fingers into the baggie and, like misbehaving children, greedily licking them clean. This is Molly, they explained: pure MDMA. The beloved molecule that you hope you're getting, but often aren't, when you buy Ecstasy.

"No one was really asking, 'Is it pure, is it chill?'" Blake says. "They were just diving right in." So he dabbed some powder on a fingertip and licked it off. A raw-chemical awfulness sucked at his jaw, then faded...

Half an hour later, as Blake dangled his bare feet in his host's pool, a blossom of euphoria spread through his chest, then closed over his head, as though he'd ducked under the water in a Jacuzzi. Blake felt his senses waking up and sharpening. The lightest of breezes stirring on his skin set off little shivers of pleasure. Time slowed to a lazy, lush haze, passing weirdly. His friends, strolling poolside, were tipping more Molly into their champagne flutes, but Blake felt no need to chase the dragon—it was curled up in his lap.

"With coke, weed, and Ecstasy, there's always some uncertainty, but I've never had a bad experience on Molly," says Blake, who's since become a recreational user—occasionally dosing with celebrities at Soho House and at parties full of artists in the Hollywood Hills. "People are looking for more of a sure bet, and that's Molly—the least amount of worry and the best possible outcome."

If a generation's drug of choice reveals something about an era's zeitgeist, it's natural that Millennials, who grew up with anxieties about hormone-laced milk and genetically altered tomatoes, would latch on to the purity of Molly. Of course, that "purity" is manufactured in a laboratory, but that provides a clue to the effectiveness of its new brand name: Molly, short for molecular, serves as a sort of seal of authenticity among discerning types for whom provenance deeply matters. They speak of their experiences in the reverential tones with which oenophiles discuss terroir; if MDMA is Pinot Noir, then Molly is a grand cru. They'll tell you it's free of the additives and fillers (which range from methamphetamine to ibuprofen to talcum powder) that can make an Ecstasy roll such a grinding, sweaty ordeal. Selling for $15 a "point" (or 0.1 gram), a single dose will flood your brain with serotonin, dopamine, and norepinephrine, lifting you a few hundred thousand feet clear of hang-ups and anxiety. Thus borne aloft, you won't feel any speed-freak compulsion to jog in place to Dutch techno or babble on about "energy flow," because while Molly reveals the profound depths of your emotions, it leaves intact your ability to express them. And unlike with Ecstasy, converts say, the landing is as soft and gentle as the takeoff.

One thing they might not be fully aware of, however, is that the name Molly appeals to their self-image just as much as it conveys something about the product itself—Molly is the clear-eyed hipster girl next door, whereas Ecstasy is more like the shagged-out stripper. "That's the brand impact of the word Molly," says Hamilton Morris, host of the online TV show Hamilton's Pharmacopeia and a radical purist who advocates using exclusively technical terminology when naming drugs. "I can't say with certainty that I would dislike anyone who says 'Molly,' but that does seem to be a general pattern. They're acting as if they have something new."

Indeed, MDMA has been "pure" before—as Adam, XTC, or Ecstasy—but every time the drug's popularity reaches a critical mass, the supply inevitably gets corrupted and MDMA's outward-facing brand image takes a big hit. Then, about every decade, it makes a comeback. "We're in the third cycle of MDMA use," says Nathan Messer, the chairman of the nonprofit organization DanceSafe, which has been testing pills at raves since 1999. "The first cycle was in the mid-1980s. Then the acid-house scene came along, which begat the rave scene that peaked in the late 1990s. Now we're back to seeing the usage that we had in 2000." When Jay-Z gave the molecule a shout-out ("MDMA got you feeling like a champion") in 2009's "Empire State of Mind," a new breed of psychonauts were already learning from drug-geek sites like Erowid.org and Bluelight.ru how dangerous street-slug X had become—and about Molly, the new pure alternative on the scene. And as hundreds of thousands of next-gen ravers flock to festivals like Electric Zoo in New York, Ultra in Miami, and the roving Electric Daisy Carnival, the word is spreading even more quickly, such that today, a new kind of user has joined the MDMA love parade: the sort of conscientious folks who eat only organic and drink only fair-trade.

"It's like emotional psychedelia, but it has none of the negative, intimidating effects that other drugs, even weed, can have," says Caleb, a 26-year-old portrait photographer based in New York City. "It's a perfect drug." Like a window-box gardener discussing his heirloom basil, Caleb (who asked that his real name not be used) seeks out Molly that isn't a powder but an uncrushed yellow-amber crystal fresh from the chemist. (According to Morris, "People have this false idea that a powder is somehow inherently more pure than a tablet. But once a tablet's been pressed, it can't be adulterated, whereas a powder can be stepped on or cut by every single person who touches it.") If Caleb's buying a capsule from someone he doesn't know, he insists on opening it up and touching a few grains to his tongue. "If it's pure," he says, "it makes your cheeks tense up, which is the weirdest thing. But that's how you know." If the dealer won't let him try it first, "I don't fuck around with it."