By The Light of the Moon by Dean Koontz
On the road, on a hot Arizona night, Dylan O’Conner is overpowered by a stranger who injects him with an unknown substance. All he’s told is that he’s the “carrier,” not of a disease but of something wondrous that will transform his life in remarkable ways—if it doesn’t kill him in the next twenty-four hours. Now Dylan, his autistic brother, Shep, and another “carrier,” a young woman, are swept into a desperate search for the shattering truth of what they are and what they might become. But first, they must elude those sent to destroy them. Their only chance to survive is to discover the meaning of the messages that Shep, with precious time running out, begins to repeat, about a man who does his work by the light of the moon.