FBI Special Agent Meg Jennings works with Hawk, her loyal search-and-rescue Labrador, as part of the FBI's elite K-9 unit. When a bomb rips apart a government building on the National Mall in Washington D.C., it takes all of the team's extensive search-and-rescue training to locate and save the workers and visitors buried beneath the rubble. The bomber remains at large, striking terror across the Eastern seaboard. As more bombs are detonated and the body count escalates, Meg and Hawk are brought in to a task force dedicated to stopping the unseen killer.