Nick McQueen is a contract agent with the CIA.
Well, he is and he isn't.
As the series begins, he is an unemployed reported, recently let go in the Los Angeles paper he had worked for during their latest round of downsizing. He was released largely because he really was not liked and he was not really liked because he was a caustic ... ah ... jerk.
We find in very short order that his marriage is finished as the lady got tired of his constantly being out of work and his constantly being himself. He is out of a home, out of a family, out of a job, out of friends (if he ever really had any), and $300 dollars away from being out of money.
And then his brother shows up and we find that we can list that man, Barry, as yet another person who really does not like Nick McQueen. Except now Barry, who works for the CIA as a hitman but pretends to be a reporter like his estranged sibling, needs his help so an offer of temporary employment is made and Nick, being so desperate, takes it. [By the way, we find out around that time that Barry is also not really liked very much for largely the same reason so it really begs the question of their upbringing.]
McQueen (Nick, not his brother) is 32 in the first adventure and has apparently already seen a lot in his adult years but what he sees in the next one is a whole lot more and before it is done, Nick will become a hitman like his brother.
Even after his line of work changes, his ability to really annoy just about everyone remains quite high. At times it seems he gets along better with his enemies than his so-called associates and friends, and those guys try to kill him a lot.