The press on my chest is an elephant's foot now. It bears down on me, the weight of a thousand beasts. There is nothing more I can give her. Almost nothing I can give myself. At last, I do the only thing I can. I take the mask that would have been hers and strap it to my own mouth, gulping its burst of oxygen in huge, desperate swallows, praying for this nightmare to end. The catastrophe has been predicted for decades. But it arrives with a swiftness no one expects. On an otherwise beautiful October evening, the air at high altitudes suddenly becomes unbreathable, depleted of oxygen. The consequences are devastating. In the United States alone, 12 million people die, almost instantly. Energy executive Martin Fall is with his family in Denver on the day of The Catastrophe. Miraculously left alive, he begins the long journey home to Los Angeles, as society begins collapsing all around him. Within months, the city becomes an armed compound, teeming with 80 million migrants fleeing for the safety of lower altitudes. Fall is lost among them, struggling for a reason to go on. But soon he has no choice. Trapped in a web of lies from those he trusted, allied with others he barely knows, he must risk his life for a technology he scarcely comprehends--one that may be the world's only salvation.