J.D. Tuccille reviews Floating City: A Rogue Sociologist Lost and Found in New York's Underground Economy. The book is a memoir of sociologist Sudhir Venkatesh's years spent penetrating New York City's vast underground economy, with an emphasis on cocaine and sex. Black markets have always existed to provide goods and services that people want and that governments don't want them to have, says Tuccille. Floating City is a fascinating glimpse at just how adaptable and real those markets are.