Jack Stone is an agent with NASRU.
That acronym stands for the North American Security Response Unit. The organization is run by General Armstrong Miller. NASRU is an agency "so covert even the President didn't know we existed. We had the best operatives in the country. We had the best technology in the world. We were above the law. We saved the lives of thousands of citizens on a daily basis without them ever knowing. We were the super-spies of the 21st Century."
The actions of Stone working for the NASRU take place three decades in the future. Stone explains that he is a lieutenant in NASRU, "technically desk-bound but often hands-on with assignments". He has several field agents working for him, chief being named Hera because "like all field agents, she had been assigned a codename from Greek mythology".