When publishers send bound galleys along to reviewers, they slip in acclamatory publicity sheets, gushing corporate lauds that often strain credulity. But the one folded into the galley of Katherine Boo's astonishing new book, "Behind the Beautiful Forevers: Life, Death, and Hope in a Mumbai Undercity," while lauding plenty, claims far too little. That's how fascinating and virtuosic, and good-quirky this book is. The release starts: "New Yorker writer and Pulitzer Prize-winner [and MacArthur Fellowship winner, too!] Katherine Boo ... [has written] a landmark work of narrative nonfiction that tells the dramatic and sometimes heartbreaking story of families striving toward a better life in one of the twenty-first century's great, unequal cities." Well, that scratches the surface of its quality.

To accomplish this writing, Boo has performed a feat of access and candid reportage that amounts to a devotion. She gained the trust of a tight community of low-caste hut-dwellers, "the ribby children with flies in their eyes," garbage pickers and sorters, prostitutes, scavengers and thieves, occasional hotel menials -- all squatters on a boggy crescent called Annawadi, hard by Mumbai Airport's luxury hotels. She followed their desperate daily lives for three years, as they came to be dear to her, whole, human and in terrible fixes. She is interested in the persistence and crushing of hope among the children. One drinks rat poison; another is capriciously accused, along with his father, of immolating a deranged, one-legged neighbor, and they end up in the hands of the corrupt police, who will see things their accusers' way, unless bribes are paid, influence is bought, and incredible months of hardship and cruelty endured.

Boo has dissected, as if with scalpel and forceps, the stabilizing anatomy of corruption, how greed and need -- in a context of desperate poverty and dim opportunity, restrictive religious certainty and a millennial, opportunistic inter-sectarian rivalry that can't afford much compassion -- govern the survival of all in the village, especially anyone industrious, anyone who reaches for education or comes up with a scheme to make a bit of money.

And Boo has sculpted her reporting and language and ingenious structuring of the revelation of events (she literally runs the clock backward in one virtuosic passage) to bring us onto the streets and into the tense minds of her characters, though their lives are far from most Western readers' experience, in their difficult corner of urban brutality.

Describing the corrupting of the least of local officials by her next-in-command, Boo writes, "He asked her to handle a petty Annawadi problem, and then another, somewhat less petty, and yet another, not petty at all, at which point he gave her a bouquet of flowers and his fat wife started giving her the fish eye. Asha took these things to be signs of an imminent triumph." Meanwhile, our accused is hiding out, "mule-brained with panic." The spring is wound. Corruption vs. a hopeful kid. You take it from there.

Mark Kramer is writer-in-residence in Boston University's Journalism Department, and director of its conference on narrative journalism: www.bu.edu/com/narrative.