• Nonfiction. By William T. Vollman. Ecco/HarperCollins, $29.95. Grade: A

Book in a nutshell: There's no doubt that National Book Award winner Vollmann is a genius, one of America's greatest living writers. He's capable of transitioning between fiction and nonfiction as if both formats were interchangeable alternative realities that could be explored with clean, unadulterated prose that cuts to the bone.

The author's ability to capture and elucidate the human experience probably reached its zenith when he wrote his 3,000-plus page, seven-volume exploration of violence, Rising Up and Rising Down, which gave Marcel Proust a run for his money when it came to breadth of vision.

His latest journalistic endeavor - following 2005's fictional recreation of fascism, Europe Central - is the relatively concise Poor People, a globe-trotting investigation of poverty's roots and consequences, for which the author traveled to six continents.

His vignettes are character studies of the dozens of people he met on his journey, living at or below subsistence level and making ends meet by living on the streets, turning to crime or simply suffering from diseases that lock them out of the wealth equation Americans take for granted.

Vollmann asked each of his subjects a simple question: Why are you poor? The responses he got reflect a gamut of emotions and justifications, which the author simmered down to a number of chapter headings, including "Invisibility," "Unwantedness," "Deformity," "Pain," and "Estrangement."

Vollmann's particular leit motifs are clearly in evidence here. His fascination, perhaps even fetish, for drug addicts and prostitutes come to the fore in Poor People, because they are always the unwanted and the unwashed in the planet's grand scheme of things.

Best tidbit: Vollmann explores Chinese illegal immigration to Japan, a mirror of our own Mexican problem, detailing sinister pimps and slavers called Snakeheads that regulate the black market in human flesh in Tokyo's underground.

Pros: The author has traveled to the four corners of the earth, staying in hotels, but spending his time interacting with (and giving money to) the impoverished, as if on a rich man's vacation set in the ninth ring of Hell.

Cons: This book is about poor people, living in shacks and cardboard boxes, and their pain and misery is real. If you can't handle that, don't read this book.

Final word: The author's wordcraft is plain spoken, but his empathy is profound; he penetrates to the heart of his subject matter, transporting readers into human suffering and making them feel like they're there.