In the span of five violent hours on August 29, 2005, Hurricane Katrina destroyed major Gulf Coast cities and flattened 150 miles of coastline. Yet those wind-torn hours represented only the first stage of the relentless triple tragedy that Katrina brought to the entire Gulf Coast, from Louisiana to Mississippi to Alabama. First came the hurricane, one of the three strongest ever to make landfall in the United States -- 150-mile-per-hour...