If the opening line of a book read, "I woke up at about 7:30 am in a crack den", and you assumed it was fiction in the mould of Kafka, you could be pardoned. But only this is the path-breaking work of sociologist and urban ethnographer Sudhir Alladi Venkatesh, a professor at Colombia University. The book, Gang Leader For A Day, an acclaimed study on illegal economies in Chicago. Crack den, by the way, is a derelict apartment used by street gangs for selling drugs, alcohol, sex and other underground wares.

Sudhir, a 23-year-old grad in 1989, spent seven years living with the dangerous and down-and-out black neighbourhoods for this project. His idea of sociology far extends the realms of data acquired through surveys;it is about feeling and experiencing the anxieties of marginalised communities. He did, though, start his first day in research with a clipboard and a set of questions and truly enough, faced hostility from the gangs. But he went back again with a steely resolve to hang out with them. There isn't much uptalk in the mean streets, he learnt. The dangers lurked too - he was caught in a few gun-battles.

The book's in-your-face narration and unforeseen truths startled the academic world. Freakonomics drew on his findings in "Why Do Drug Dealers Still Live With Their Moms?" Sudhir's other works on the underground economy and the rise and fall of the modern ghetto have also explored lives in his trademark style. Sudhir's daring approach as an ethnographer has had Freakonomics co-author Stephen Dubner see two abnormalities in him: "an overdeveloped curiousity and an underdeveloped sense of fear".

He was born in India but came to the US when he was five and grew up in a California suburb. Now he likes to think of himself as an American.