Journalists delight in metaphors that sum up an entire story with one striking image. In Mumbai, itself a neat nutshell of India\'s extremes, this image is served on a platter: the shiny towers that rise from a sprawl of squalid slums, the two inevitably \"jostling for space\" in globalising India. This picture is deployed for all sorts of stories, whether social, political or economic, and in any number of publications including this one. Katherine Boo has written about poverty for two decades. She is not immune to the power of this image of extremes. But instead of using it as a backdrop, her first book, Behind the Beautiful Forevers, makes the metaphor the story. Why, she wonders, is this juxtaposition of wealth and poverty considered a moral problem and not a practical one? How does it persist? \"Why don\'t more of our unequal societies implode?\" In search of an answer, Boo zeroed in on Annawadi, a small slum surrounded by imposing five-star hotels near Mumbai\'s international terminal. The book opens with Abdul Hussain, a young garbage trader, hiding in his shed. His family of 11 had been on the move. Their garbage business was thriving and they had made a down-payment on a plot of land in the far suburbs. But then his mother had an outsize ambition: in a house too small for every member to sleep indoors, she wanted a nice kitchen. It was while doing the wall, which the Hussains shared with a one-legged neighbour, that the fight started. \"If you don\'t stop breaking my house ... I will put you in a trap,\" said the one-legged woman. In a bizarre retribution, she set herself on fire. The Hussains, accused of her murder, eventually lost their garbage business amid jail terms and court dates. Aspirations are everywhere in Annawadi, \"as if fortune were a cousin arriving on Sunday\". In a nearby hut lives Asha, a feisty woman who wants to make corruption work for her by becoming the conduit between councillors and the community. Her daughter, Manju, is only a few exams away from becoming the slum\'s first woman to gain a bachelor\'s degree. All of humanity — corrupt policemen, pre-teen scavengers, cunning thieves, crooked nuns, minor politicians, Bollywood stars, disinterested judges and lots of noisy neighbours — flits in and out of the orbits of these two families. Through them, Boo explores poverty, corruption and the hope of upward mobility that globalisation brings. In introducing the reader to the depths of urban Indian poverty, Boo is unsentimental but evokes compassion. The degree of corruption she uncovers is horrific yet unflinchingly reported. But it is when she explores the theme of hope that Boo answers her question about how such economic disparities are sustainable. Ambition in the slums is undercut by rivalry; aspirations are met with local resentment. \"The poor took down one another,\" she observes. Her pages are filled with examples, but it is the story of the vindictively suicidal one-legged woman that drives this point home. The Hussains pay dearly for dreaming of a better life. Meanwhile, the towers of what Boo calls the \"overcity\" glimmer unscathed. The riots that occasionally inflame India destroy the poor neighbourhoods but leave the wealthier parts of town untouched. Boo blames \"government priorities and market imperatives\", which \"create a world so capricious that to help a neighbour is to risk your ability to feed your family\". But this feels thin. Mumbai\'s poverty is not new. Slums sprouted skyscrapers long before prosperity came to India. Nor are the government\'s priorities anti-poor; it is corruption that renders them ineffectual. When India\'s economy was closed, the country was a moribund, hopeless place. The swirl of new money flowing through the streets may have added many zeroes to every corrupt transaction. But hope has grown many times faster still. That is surely no bad thing. Behind the Beautiful Forevers: Life, Death, and Hope in a Mumbai UndercityBy Katherine BooRandom House, 256 pages, $27