The Stand by Stephen King

 The Stand

Synopsis: This is the way the world ends: with a nanosecond of computer error in a Defense Department laboratory and a million casual contacts that form the links in a chain letter of death.

And here is the bleak new world of the day after: a world stripped of its institutions and emptied of 99 percent of its people. A world in which a handful of panicky survivors choose sides or are chosen. A world in which good rides on the frail shoulders of the 108-year-old Mother Abigail and the worst nightmares of evil are embodied in a man with a lethal smile and unspeakable powers: Randall Flagg, the Dark Man.