John Lincoln is an agent for the Treasury Department.
He is one of the Hooligans, the name given the member of the Special Service, a section in the Treasury Department responsible for going to exotic places and doing interesting things there in the interests, usually economical, of the American government.
When he joined the Special Service, he was told clearly that "you're all expendable, in whole or in part. We don't urge you to expend yourself, however."
Physically, Lincoln is described as a "big, spare, homely man in his mid-thirties." He is always dressed nicely and appropriately, his hair is routinely cut and he is clean shaven. The item of his looks that turned plain into homely was his teeth which bulged when his lips were closed. It was enough to set some people ill at ease around him.
Lincoln's area of expertise is the Far East with a specialty on Hong Kong. He is fairly good at his job and well respected for it but after nine years working there, he had yet to see any really interesting, read 'dangerous', work. He was, he muses, trained in firearms and fully qualified to kill but had never fired a weapon outside of practice. He was bored.
Apparently, being bored as a Hooligan is not a good thing. Lincoln is sent on a very strange mission in which he is told an overall objective but not given any suggestion as to how to accomplish it. This would seem the way that the Hooligans normally operated.
Lincoln is very good at his job, which is how he survives, but his job is very difficult, which is why he barely does the surviving.