Airport Ranger volunteer Stacy Broussard expected a peaceful Saturday morning ride around the perimeter of Houston's airport. What she encounters instead is a brutal homicide and a baffling mystery. Next to the body is an injured dog, the dead man's motorcycle, and a drone armed with a laser capable of taking down a 747. Though FBI Special Agent Alex LeBlanc sees a clear-cut case of terrorism, his past has taught him to be suspicious of everyone, even witnesses. Even bleeding-heart veterinarians like Stacy. But when her gruesome discovery is only the first in a string of incidences that throw her life into a tailspin, Alex begins to wonder if Stacy was targeted. As a health emergency endangers Stacy's community, and the task force pulls in leads from all directions, Alex and Stacy must work together to prevent another deadly encounter.