Katrina was not the last hurricane to devastate New Orleans. A decade passed while the city rebuilt, and then six more hurricanes destroyed the whole region. After the hurricanes, the Delta Fever broke out. Eventually the gulf coast was quarantined, and then evicted from the United States. Half a century later, Fen is a young girl surviving with her tribe, until the night another tribe attacks. She's alone, save for her dead friend's newborn baby, and a researcher who is more helpless in Orleans than the child. And Fen's responsible for ushering them both to safety. 
 Engrossing and yet slow-moving and somehow easy to put down. But the world is well-built, and Fen never even THINKS about falling in love with the stranger (and seems to find him something of a pain in the ass), so yay for those aspects of an apocalyptic novel for teens. 
 One thing that bugged me: several references to Katrina hitting while the city was still reeling from Rita. Which in reality happened a few weeks AFTER Katrina. There was so much care in building the world and grounding it in accurate details that this glaring error in chronology grated on me every time I read it.