"This is the view that most of those guys in high-rise office cubicles are dreaming about," says Brooks, a 39-year-old Seattle native, gesturing toward the fluted green mountains of the Na Pali coast and the Pacific, which laps at a mile-long stretch of beach in the distance. It's a warm day in June, and Brooks (who asked that his last name not be used) swings in a hammock on a ridge overlooking the Kalalau Valley on the north shore of Kauai, Hawaii's oldest island, where he's lived since 2006. Despite owning five properties in Washington State, Brooks lives here because the lifestyle offers "the truest sense of freedom. I've gone into early retirement," he says, flashing a Hollywood smile. Barefoot and wearing cut-off board shorts, with a bronzed chest and ripped abs, Brooks could pass for a Venice Beach bachelor—except he has no car, television, or cell phone, hunts wild animals for his meals, and counts himself part of a little-known and loosely agglomerated community called the Outlaws, who inhabit this remote hidden valley.

To reach this slice of paradise, you follow the 11-mile Kalalau trail, pass five canyons that drop into the sea and terraced hillsides brimming with mango and guava trees, scramble up a red-dirt hill, and then behold it: a lush valley, like in a Frederic Church painting, that recedes into scalloped mountainsides laced with waterfalls and draped in fragrant plumeria flowers and passion-fruit trees. After a hike down to the beach, a quick survey reveals the bounty: tomatoes and wild basil line the trail, and a pristine freshwater stream flows, teeming with prawns and watercress. In a very real sense, it is the land of plenty.

Philosophers, artists, and writers have long mused about man's search for an earthly paradise. Sir Thomas More's Utopia described a fictional island society and gave us a colorful new word, while James Hilton's 1933 novel Lost Horizons introduced Shangri-La, a mystical valley where the inhabitants enjoyed serious longevity. As for the modern-day model, well, if Leonardo DiCaprio were looking for a real-world version of The Beach, he'd find it in Kalalau.

Here, the Outlaws—spiritual seekers, burned-out professionals, social outcast—live a back-to-nature lifestyle, drinking wine made from passion fruit, sucking on fresh mangoes, roasting wild boar and goat (the testicles are a Thanksgiving treat), while operating a barter economy for those necessities the valley doesn't provide (tobacco is highly prized). Topless women roam the riverbanks offering massages in exchange for weed, psychedelic mushrooms, and LSD. When I arrived last summer to live among the Outlaws for 10 days, one such woman greeted me with "Bless your way, goddess."

For travelers and professionals from around the globe who hike to the end of the trail, the rewards are immediate. "It's like going back through time," says Heath Haacke, a 36-year-old attorney from Park City, Utah, who is packing up after a four-day stay to recharge. Will Smith owned a house close by, and Mark Zuckerberg was recently hunting for a home near the valley, which, as part of the Na Pali Coast State Wilderness Park, lies on public land. Shortly before he signed up for The Secret Life of Walter Mitty, about an office-bound daydreamer yearning for an adventurous life, Ben Stiller hiked the Kalalau trail, describing it as "beautiful" and "frightening." Pierce Brosnan celebrated his 50th birthday with the Outlaws, enjoying their signature cake under a lunar eclipse.

A prime camping spot near the beach, under the shade of a kamani tree, whose nuts taste like almonds. Fresh water, seafood, wildlife, and fruit abound in the Kalalau Valley—bounty for an idyllic back-to-nature lifestyle.

For years, the Outlaws were able to keep their existence a relative secret, living peacefully and abiding by basic commandments. "Don't steal. Be respectful. Don't bring violence to the valley" is how Red, a 39-year-old professional musician and Outlaw from Hopatcong, New Jersey, summarizes the tribal code. For the most part, the self-policing worked and the Outlaws lived under the radar, albeit illegally, as squatters in a national park. But that changed one evening in December 2012, when a recent arrival named Justin Klein, a handsome 37-year-old drifter from Eugene, Oregon, hiked with a couple of Japanese tourists to the valley's heiau, a holy structure on a steep promontory built 1,000 years ago by Polynesians, who performed rituals at these sacred spots, including human sacrifice. On this night, Klein allegedly threw one of the Japanese women, who had recently become his lover, off the cliff—setting in motion a chain of events that would push the Outlaws' seemingly idyllic society to the brink of collapse.

• • •

Shortly after dawn on Halloween 2012, Justin Klein woke to the sound of a goat braying. Klein, six feet one, lean, and sporting an impeccably groomed mohawk and goatee, was camping by the beach, about 50 yards from A Camp, the social hub of Kalalau's loose-knit community and the home of its de facto chief, Alekai Kinimaka, a 53-year-old hard-drinking, pot-smoking former pro surfer with a penchant for playing the ukulele. The goat was caught in another man's snare, and although stealing is a serious transgression among Outlaws, Klein decapitated the animal with a machete and claimed it as his own.

Klein had arrived in Kalalau a few weeks earlier and was often found hanging around A Camp, a tarp-roofed compound overlooking the beach with two open-fire grills, several hammocks, folding chairs, and coolers stocked with Gatorade, eggs, bacon, and cold beer. Newcomers would often perform chores for Kinimaka in return for access to his supply of food, booze, and weed. He collected water, kept the camp tidy, and cooked meals for Kinimaka and his guests. Klein was born in Oregon and spent much of his adult life there. After dropping out of high school in his junior year, Klein opened a successful landscaping business in Eugene, where he lived in a house on 12 acres with a small farm—he was an avid outdoorsman and hunter. At 19, he got married, and he and his wife went on to have two daughters. Around 2008, his marriage, and then his business, began to implode. He spent the next several years flailing around town before deciding, in May 2012, to seek a fresh start in Hawaii.

But Klein couldn't settle, and after four months of exploring the islands, he landed in Kalalau. He didn't arrive with much gear or many material possessions to barter with, so he survived by getting things—food, shelter, tools—from others. "He was intelligent, was a good-looking guy, and he was helpful," says Larry, 49, a former Coast Guard helicopter mechanic who has lived in Kalalau on and off since 1996. Sometimes, however, Klein exploited others to get what he needed, according to Richard Pecjak, a 50-year-old photographer from San Diego who was friendly with Klein during a three-week stay. "He was a master manipulator, and he didn't really have anything to contribute except his Charles Mansonesque personality," Pecjak says.