Barrett Mason is a private investigator.
Well, a couple of times during the period we follow him he is. Other times, he is a U.S. Marine sergeant. And a CIA trainee. And then neither but still a bit of both. Then a federal prisoner, followed by being a private eye and you might be getting the idea. It sounds like the man cannot keep a job but the truth is a whole lot meaner.
At one point early on in the first recorded adventure we have of mason, he lets us know that "I wasn't an official member of anything. At least, nothing the US government would acknowledge. I wasn't CIA, or NSA, or any other three letter organization which was a recognized part of the US intelligence community. You could say I'm a Marine. Not in active service. Those days are far behind me. But the skills I learned as a part of Force Recon have come in particularly handy, given my current career." He also mentions about his "long un-history of service with the US government".
Mason had been for a few years a member of the Marine Force Recon. Exactly how long I do not know but it was long enough to have made it into that elite division and enough to get the rank of Sergeant but not enough to achieve Gunnery Sergeant yet. He was assigned to the protection detail of the US ambassador to Yemen when a terrorist attack killed that diplomat and almost ended Mason's life. That will be followed by a brief liaison with the CIA going after those same terrorists. After that his life will have more ups and downs than a roller coaster.
Before you get the idea that Mason is at all a foul-up, rid yourself of that idea. This is a good man who does good things for good reasons which sometimes runs afoul of not-so-good people doing very bad things. Usually this is a positive. When those bad people are in powerful positions, though, it often does not work out so well.
Mason grew up in Texas and spent his teenage years in Houston with just his brother having become an orphan while in middle school. "My brother and I were left to fend for ourselves in the roughest neighborhood ... I was used to good things crumbling to s**t."
One of those things that crumbled away was his marriage to Libby but as the adventures go by he will be reunited with her and they will be joined by Kejal, a young girl he rescues. Many of the unpleasant things that we will watch happen to him will come because he refuses to let bad things happen to them.
"I've learned not to try and read the CIA's mind, or I might end up with my brain fried like half of them. They're all so weird and secretive - it's like a cult operating right under our noses."