Despite years of graphic warnings, why were US authorities so unprepared for what became one of the most devastating hurricanes in American history?
Wedneday, 12 October, 2005
2100 BST, BBC Two
"If it can happen here in New Orleans, you all better watch out man, because it can happen anywhere, " says resident Joe Salazar.
The Hurricane That Shook America is the story of the journey towards catastrophe in New Orleans.
For years, scientists had predicted that a hurricane could cause mass destruction and flooding across the city.
But when disaster struck, America was found wanting.
In 2004, the Federal Emergency Government Management Agency (Fema) had organised a full-scale computer exercise for hurricane emergencies which predicted problems with the levees and serious floods.
And yet its director, Michael Brown, admits he was shocked by the squalor that developed at the city's Superdome.
In an exclusive interview he tells the BBC: "It was absolutely a fascinating phenomenon to see that as the disaster continued to grow - as the flood waters would grow and then recede - people would escape from their homes and go to the shelter."
Confusion and anger
New Orleans, built in a natural basin and surrounded by water, is protected from flooding by a delicate system of levees.
The Hurricane That Shook America reveals that these levees were not engineered to withstand a storm of Katrina's strength.
In a rare interview, an insider from Fema says the blame lies with incompetent leadership.
Emergency planners speak candidly about the impending disaster: who knew what, and when, as the devastation drew closer.
And the film-makers also find Jabbar Gibson, a young black man who steals an empty school bus to drive a group of homeless children out of the city.
His story, like many others, is one of confusion and anger at the government's slow response and neglect.
Katrina stunned America... and America stunned the rest of the world.
Executive producer: Karen O'Connor