On the western edge of Frozen Head State Park, just before dawn, a man in a rust brown trench coat blows a giant conch shell. Runners stir in their tents. They fill their water pouches. They tape their blisters. They eat thousand-calorie breakfasts: Pop-Tarts and candy bars and geriatric energy drinks. Some of them pray. Others ready their fanny packs. The man in the trench coat sits in an ergonomic lawn chair beside a famous yellow gate, holding a cigarette. He calls the two-minute warning.

The runners gather in front of him, stretching. They are about to travel more than a hundred miles through the wilderness—if they are strong and lucky enough to make it that far, which they probably aren’t. They wait anxiously. We, the watchers, wait anxiously. A pale wash of light is barely visible in the sky. Next to me, a skinny girl holds a skinny dog. She has come all the way from Iowa to watch her father disappear into this gray dawn.

All eyes are on the man in the trench coat. At precisely 7:12, he rises from his lawn chair and lights his cigarette. Once the tip glows red, the race known as the Barkley Marathons has begun.

I.

The first race was a prison break. On June 10, 1977, James Earl Ray, the man who shot Martin Luther King Jr., escaped from Brushy Mountain State Penitentiary and fled across the briar-bearded hills of northern Tennessee. Fifty-four hours later he was found. He’d gone about eight miles. Some might hear this and wonder how he managed to squander his escape. One man heard this and thought: I need to see that terrain!

Over twenty years later, that man, the man in the trench coat—Gary Cantrell by birth, self-dubbed Lazarus Lake—has turned this terrain into the stage for a legendary ritual: the Barkley Marathons, held yearly (traditionally on Lazarus Friday or April Fool’s Day) outside Wartburg, Tennessee. Lake (known as Laz) calls it “The Race That Eats Its Young.” The runners’ bibs say something different each year: SUFFERING WITHOUT A POINT; NOT ALL PAIN IS GAIN. Only eight men have ever finished. The event is considered extreme even by those who specialize in extremity.

II.

What makes it so bad? No trail, for one. A cumulative elevation gain that’s nearly twice the height of Everest. Native flora called saw briars that can turn a man’s legs to raw meat in meters. The tough hills have names like Rat Jaw, Little Hell, Big Hell, Testicle Spectacle—this last so-called because it inspires most runners to make the sign of the cross (crotch to eyeglasses, shoulder to shoulder)—not to mention Stallion Mountain, Bird Mountain, Coffin Springs,...