Thomas Caine is an agent with the CIA.
That is true. And false. And sort of true again.
He was an operative with the Agency some time back. Paramilitary in nature, sent in to do all sorts of black-ops things no one talks about because officially they never happened. When things got especially tough, if not impossible, that is when Caine was called because he was especially good at getting accomplished these things that were not happening.
And then suddenly he wasn't. According to the records, the emerald-eyed Thomas Caine was on an op in Afghanistan where he "was posing as an arms dealer, to make a connection with the White Leopard drug cartel in Afghanistan. According to his handler's report, he went rogue. Killed his partner and disappeared with a shipment of guns and heroin. Then he resurfaced and tried to sell it on the black market. When the White Leopards found out who he really was, they killed him and took back their drugs." So as far as everyone thought, Caine the rogue was dead.
Things are often not how they appear in the cloak and dagger world and that is definitely the case with Caine. He is not dead, of course, but there are some very powerful people who would like him to be and he is as determined to thwart them at that and Caine is very, very good at staying alive. Still, even he can find himself in a very unpleasant situation and when that happens to him in Thailand, he becomes amenable to an offer by a CIA officer in need of someone with Caine's unique skill set.
Caine is smart enough to know when a lifeline is thrown to a drowning man, he grabs it or perishes, no matter who is tossing it. It makes for a very interesting situation, though, as it becomes slowly clear that someone in the organization that hired him in the first place, then set him up for a huge fall, and then hires him again is a very bad man. Caine wants to find that man.