Anne Montgomery 
Light in the Desert [EPUB ebook] 

As a Vietnam veteran and former Special Forces sniper descends into the throes of mental illness, he latches onto a lonely pregnant teenager and a group of Pentecostal zealots – the Children of Light – who have been waiting over thirty years in the Arizona desert for Armageddon. When the Amtrak Sunset Limited, a passenger train en route to Los Angeles, is derailed in their midst in a deadly act of sabotage, their lives are thrown into turmoil as local and state police, FBI investigators, and a horde of reporters arrive on the scene. As the search for the saboteurs heats up and the authorities question members of the cult, they uncover more questions than answers. And then the girl vanishes. As the sniper struggles to maintain his sanity, a child is about to be born deep in the wilderness.