Every morning at my parents' condo in South Carolina, alligators appear in the back yard. Lying statue-still in the crisply cut grass, they look as fanciful as unicorns, though unicorns wouldn't snatch neighbors' poodles or lunge at the lawn mower. Forty years ago, my little brother and I used to feed them marshmallows (illegal now; incredibly stupid then). In one of our old 8mm home movies, you can see the sugary white dots disappearing as a seven-foot monster glides through the water before turning sharply toward the shore where we're standing. A hail of marshmallows rains down as the alligator runs up the bank - then the empty plastic bag, then the screen lurches and goes black.

Karen Russell's first novel, "Swamplandia!," took me back to that surreal childhood encounter. With a mixture of comedy, terror and nostalgia, she conjures up a run-down theme park 30 miles off the Gulf Coast of Florida, a tourist trap run by a family of phony Indians named the Bigtrees: "Catch the late show, Saturdays. Alligators! Starry nights! It's like Van Gogh meets Rambo." Indeed, this is no Disney World; the major attraction is "Live Chicken Thursday," when alligators leap out of the water to snatch hens from a clothesline. People come by the hundreds for a swampy serving of grotesque death and macabre slapstick. An experienced alligator wrestler, Chief Bigtree, warns that the reptile "can hoard its violence for millions and millions of years. . . . It's pure appetite in a leather case."

Russell's work has appeared in "Best American Short Stories," and she's been blessed by the New Yorker, Granta and the National Book Foundation, so this is a debut with an unusual amount of momentum behind it - all well deserved. If you read "St. Lucy's Home for Girls Raised by Wolves" (2006), you'll recognize this novel as an expansion of the opening story in that celebrated collection. But at more than 10 times the original story's length, "Swamplandia!" gives those giant lizards room to roam.

As the novel begins, Mrs. Bigtree, who dazzles spectators by diving into a dark pool of several dozen alligators, is killed instead by a fast-moving cancer. The park slips into bankruptcy, and the family stumbles around in a daze of unexpressed grief. Grandpa is consigned to a nursing home, and Dad takes off to the mainland with vague plans to raise money. "Swamplandia!" needs to dispatch its adult characters quickly because this is a story about three lost siblings, young people burdened with more responsibility, affection and sorrow than they can possibly carry alone.

Russell has perfected a tone of deadpan wit and imperiled innocence that I find deeply endearing, but readers allergic to self-consciously quirky characters should take precautions. On this almost make-believe island, the Bigtree children home-school themselves with moldy books from a Library Boat abandoned in the 1950s. They speak with preternaturally mature knowledge without realizing how little they know of the real world. One wrong move and the novel's poignancy could slip into cuteness.

Thirteen-year-old Ava narrates half the story, and she's an irresistible blend of earnestness and courage. Determined to save her family's business by winning an alligator-wrestling competition - wherever it might be - she sends letters to the Smithsonian, the state universities and the Florida Wildlife and Gaming Commission: "I was an alligator wrestler," she explains, "accustomed to bold movements. . . . I didn't brag exactly, but I made sure the commissioners understood that I was the real deal; I wasn't some unserious church girl from Nebraska who had only ever handled pet-store geckos, or some inlander, 'Rebecca' or 'Mary,' a pigtailed zoo volunteer."

But Ava's more immediate problem is saving her older sister, Ossie, whose depression draws her to spiritualism and a psychotic romance with a dead dredgeman. At the center of the novel is Ava's rescue mission through the mangrove-choked waters of the Ten Thousand Islands in a 14-foot skiff. Russell is trafficking in some classic stories here, from Huck Finn's adventures down the Mississippi to Odysseus' voyage across the River Styx, and you never know when a riptide of tragedy might pull away the humor of "Swamplandia!" As in her short-story collection, she's charted out a strange estuary where heartbreak and comedy mingle to produce a fictional environment that seems semi-magical but emotionally true.

In alternating chapters, a separate strand of the novel follows Ava's older brother, Kiwi, as he tries to make his way on the mainland by working as a janitor at a competing theme park called the World of Darkness. The novel's insistence that each of the Bigtree children go to hell may strike you as a heavy-handed metaphor, but Russell has a lot of fun with this brimstone resort (the Devil's Oven concession stand sells Hellspawn Hoagies and Faustian Bargain Fish Tacos). Like his youngest sister, sweet-hearted Kiwi is a hilarious character, a bumbling, adolescent genius constantly running up against his own naivete. He's desperate to fit in, but he's handicapped by a giant vocabulary of impressive words that he's never heard out loud (he "pronounced 'ominous' so that it rhymed with 'dominoes' ").

After a lifetime on Swamplandia, he's like a space alien who knows about teen life only from reading Margaret Mead. With his childlike enthusiasm and his guileless expression of hope, he's a giant Kick Me sign among the thugs and druggies who toil away for minimum wage at the World of Darkness. "Every day, Kiwi's colleagues taught him what you could and could not say to another person here on the mainland," Russell writes. "This was a little like having snipers tutor you on the limits of the prison yard." Eager to prove his heterosexuality, while cleaning one of the rides he recites "Ode on a Grecian Urn," "believing that the beauty of the poem would be self-evident and exonerate him." Alas. And somehow, using the word "pulchritude" in reference to another janitor's girlfriend doesn't win him any points, either. "What was wrong with these philistines?" he wonders.

Despite all the charms of "Swamplandia!," pacing is a problem, as it was for Reif Larsen's "Selected Works of T.S. Spivet," another novel about a precocious child's dangerous, grief-fueled journey. Good short-story writers like Russell know how much depends on endings, those final few breaths of ineffable melancholy, but landing a novel requires something more. After half-a-dozen detours, skating along a thin layer of plausibility, Russell runs through the final pages as though she's being chased by a seven-foot gator. I know that feeling, but I wish she'd taken her time and given this finale a little more room to breathe. After all, she sends her smart, vulnerable characters to hell. We want to know just how deeply they've been singed.

Charles is The Post's fiction editor. His reviews appear every Wednesday.


By Karen Russell

Knopf. 316 pp. $24.95