Jonas Blackthorne is an agent with S.E.N.T.I.N.E.L.
S.E.N.T.I.N.E.L. is a top secret Australian intelligence organization, considered "private" because it worked outside the official channels, unknown to virtually everyone except its members and the Prime Minister and Chief-of-Staff. Its funding came from the black ops budget which is fitting because that is largely the sort of work its people did. The acronym stood for Strategic Enforcement, National Terrorism Intelligence Network, Espionage and Logistics, a significant mouthful.
As the recorded adventures begin, Blackthorne is not yet a member of this bureau being a man in need of something important to do. This highly athletic and vigorous man in his late 30s had a year and half before left the military where he had reached the rank of Major in the Special Forces elite SAS. Fourteen years of service in that branch had resulted in a stellar reputation and numerous commendations and medals.
His departure was at his own request for early release, coming after a particularly nasty operation went horribly wrong and two of his men were killed. Blackthorne blamed himself but soon learned that it had been an accidental leak by a major politician that had brought enemy forces against them. When it was decided that for the good of the country the entire matter would be dropped, he had had enough and wanted out.
Out was not something he was good at, though, and neither was sitting around doing nothing. When he is pressed into service, unofficially at the time, in the first adventure, his success will result in being offered new employment and a new career. He takes it.