Special Agent Gil Martins investigates domestic terrorism for the Houston FBI. He is a religious man who is close to losing his faith; the very nature of his job has led him to question the existence of a God who could allow the things that Gil sees every day. But Gil's wife Ruth doesn't see things the same way and his crisis of faith provokes a fracture in their marriage. Gil's world is breaking apart. At the same time, Gil starts to investigate a series of unexplained deaths that bring this crisis of faith into uncomfortable focus.