Thomas Sebastian Scott is an agent with the NSA.
When we first meet him he is recovering from a terrible car accident in which the car he was riding went off a mountain road on the Khyber Pass, killing all by him and nearly taking him as well. The accident left him with a lack of memory, such that he was surprised when he talked to the nurse in fluent Urdu, like a native. It was around then that the medicine a visiting American doctor gave him took effect and he slowly sank away and died. Mostly.
Why it was deemed necessary for Franklin Lambert, the man we are talking about, to cease to exist is part of the story, so no spoiler here, but he did and in his place is Scott.
Lambert/Scott is not a young man. He was born in 1948 which makes him in his mid 60's when the adventures take place. He is described as a "hint over six feet tall, and thin as a praying mantis". He is an expert in cyber-security having been working in that field for a very long time. We also learn that he was born and partially raised in Pakistan to American parents which explains his understanding of that nation's language and customs.
He has retired from the cloak and dagger world and moved to West Virginia where he had a serendipitous reconnect with a fellow seminarian from his much younger days, Father Sean McManus, and who is now his best friend and frequent confidante.
For an older man who has retired and left all the danger and excitement behind, this fellow still gets into a ton of trouble and has to prove over and again that being old is not the same as being helpless.
- Said by Scott, "If I've learned nothing else in 65 years, I certainly know how to make a cup of coffee".