Former human, touched by the mysterious death phenomenon spreading across the continental USA in the 2000s and transformed against his will. Its control over him isn't absolute and he's resisting to his last breath; he has a mission to stop it and he's going to carry it out, knowing full well he's not going to live to see the end. All the pieces have to be placed perfectly before that and he'll fight tooth and nail to get it done.

...Unfortunately, his own humanity is getting more and more garbled by the phenomenon itself. It's shifting him into its unwitting vector even as he chases it across the country.