"Arcadia," a Novel by Lauren Groff Lauren Groff's "Arcadia" is so immersed in the life of a hippie commune that patchouli ought to waft off its pages. It's a novel of the 1960s and "70s in which acid is dropped, groats are served, "Froggie Went A Courtin" " is sung, a cult leader is worshiped and somebody literally hugs a tree. An outhouse at Arcadia smells like wet muskrat. Children are reared in a Kid Herd. This does not sound like everyone's cup of rose-hip tea. So the transporting magic of "Arcadia" comes as a surprise. Ms. Groff has taken a quaint, easily caricatured community and given it true universality, not just the knee-jerk kind that Arcadian platitudes espoused. Even more unexpectedly, she has expanded this period piece so that it stretches from 1965 to 2018, coaxing forth a remarkable amount of suspense from the way her characters change over time. And a book that might have been small, dated and insular winds up feeling timeless and vast. The raw beauty of Ms. Groff's prose is one of the best things about "Arcadia." But it is by no means this book's only kind of splendor. Ms. Groff draws her readers into the mind of Bit, the first kid born into the midst of Arcadia's affectations. His real first name is Ridley, but he earned his nickname by being very small. "Bit" is supposed to mean "Little Bit of a Hippie." But it also describes the bit-by-bit way this book coalesces as Bit, its main character, begins to understand his surroundings. "Parts of the world click into shape, like pieces in a jigsaw puzzle," Ms. Groff writes, describing how Bit's mind works. But the puzzle is alive; it grows; new pieces appear for him to fit together faster than he can gather them in his mind. He is a 5-year-old during the first long stretch of the book, and his grasp of the adult world is limited. But Bit is a favorite of Arcadia's Hens, or pregnant women, and is not considered too young to help with childbirth. He learns all about the body long before he understands the heart, mind or soul. It takes a while for Bit to understand that his parents, Abe and Hannah, are very different from each other. In a community where sexual liaisons are free form and the concept of family is bewildering, he desperately wants his parents to stay together, though he fears they will not. Bit also begins to see that his mother is two people; he thinks of her as Summer Hannah and Winter Hannah. And Ms. Groff, who delivers insights into the people of "Arcadia" as if they too were jigsaw puzzles, gradually makes it clear why Winter Hannah - depressed Hannah, who is known for her physical strength but won't get out of bed - has come to stay. Beneath this book's dazzling veneer of commune life its true thoughts about freedom, love, fear and envy lie ready to be exposed. "Arcadia" is stunningly sensual and visceral in describing behavior straight out of a time capsule. When Handy, the group's leader, prepares to leave for a three-month tour (something involving concerts and an anatomically explicit puppet show), his "main wife" bids him farewell: "She unknots a hemp necklace from her throat and ties it around Handy's neck, kissing him over his third eye." Handy's two wives have his real children, and these kids" feelings about their father's departure are far less ceremonial. Arcadia's crop of children will grow up to be troubled and rebellious, yet they will always be bound by the strangeness of their shared childhood. "They hurtle through life aging unimaginably fast," Ms. Groff writes about the figurative parachute that keeps them together, "but each grasps a silken edge of memory that billows between them and softens the long fall." The first long segment of "Arcadia" is a shimmering evocation of the commune's heyday. Even allowing for Ms. Groff's extraordinarily rich imagination, she writes about this life as if she has known it. The main plot development at this stage is the secret rebuilding of an abandoned mansion on Arcadia's sprawling upstate New York acreage, a move planned and led by Abe even though the workers aren't supposed to have any leader other than Handy. We are right inside that house when Ms. Groff evokes "a powerful stench: varnish and polyurethane and paint, beeswax and vinegar and sweat, sawdust and copper and cold nails." And we are deeply inside Arcadia's mind-set by the time Handy comes home and reacts to what happened while he was away. In the story's next section Bit has hit adolescence. His parents" lives have drastically changed. And the outside world has begun worming its way into the commune's utopian plans. Arcadia is filled to the bursting point with runaways, indigents and drug burnouts. Guys in black leather jackets are showing up at this vegan paradise. And Arcadia's homegrown kids have attained new insights into the wider world; one boy did not know he was black until this part of the story. Eventually he will become Arcadia's most conspicuous failure by becoming a prominent neo-conservative commentator on a cable news show. Bit falls in love with Helle, Handy's daughter, during this part of the novel. He also begins falling out of love with Arcadia, though he is by far this book's most cautious and uncertain character. There are two more big-time leaps for Ms. Groff's narrative to make, and it would take plot spoilers to specify when and where this novel will touch down. Since she never resorts to foreshadowing or any other storytelling tricks, the start of each section is truly startling. But even when "Arcadia" moves into 2018 and introduces technology redolent of science fiction, it remains stirringly human in its point of view. Ms. Groff's first novel, "The Monsters of Templeton," actually incorporated an aquatic monster. Yet the impact of this creature was not simply malign. In a similar way "Arcadia" lets the 5-year-old Bit discover a book of Grimm's fairy tales and make it a secret treasure. That book comes to signify his longing for the darkness that was always all around him but could never be acknowledged by Arcadian orthodoxy. Ms. Groff uses the fairy-tale version of horror to give "Arcadia" an added pathos. When Bit equates old age and illness with a long-forgotten fable of a woman bricked into a wall, alive but trapped, he has found his way to the deep, resonant heart of the Arcadian story.