Plague Year

The nanotech was intended to save lives. Instead, it killed five billion people, devouring all warm-blooded lifeforms except on the highest mountain peaks. The safe line is 10,000 feet. Below, there is only death. Above, there is famine and war. Humankind's final hope rests with a scientist aboard the International Space Station... and with one man in California who gambles everything on a desperate mission into the ruins of the old world...