After a career in Army Intelligence, Porter Beck is back in Nevada and doing the same lawman's job his father once did. His sparsely populated jurisdiction is usually very quiet. But on the night of July 4, Sheriff Beck sees a strange light streak across the dark sky. He prays it won't crash in drought-stricken Lincoln County, where the wildfires are already burning. But it does, and the resultant explosion triggers an avalanche of death and destruction in the high desert, impacting Beck's oldest friend, the community at large, and even his sister, Brinley.
Beck's search for answers leads him to a young girl that Brinley is mentoring, a sixteen-year-old tech whiz, Mercy Vaughn, who is currently incarcerated at the local youth center. Despite all the assurances he's given, Beck senses the young hacker may be up to more than her jailers know and that she herself is more than she claims to be. And it's not just Beck: a vicious Mexican drug cartel and a brutal foreign agent also have a stake in learning the truth behind the mask that is Mercy Vaughn, and they are leaving a trail of destruction and death in their path.