Razored Land — Charles Allen Gramlich

The day after The Flux hit, Jase Holland was still alive...and immune. The world was not as lucky. The Flux was a genetic plague-possibly leaked from a biowarfare lab-and it played havoc with the DNA of every living thing, mutating genes to create monsters and strange new sentient beasts both beautiful and deadly.Jase's fiancée-Jenn-was pregnant when The Flux struck. He rushed to reach her but found his path blocked by what appeared to be demons intent on destroying the last remnants of humanity. He called them the Vile and began to wonder if something more than human hubris had triggered The Flux. What mattered most, though, was saving the woman he loved. And she was nowhere to be found.