Jonathan Hemlock is an assassin for CII.
He is also a fairly young, aged 36, university professor of art who is very popular with the students, illogically though it may be as he is caustic and unforgiving. He recognizes the irony in the fact that the more he heaps disdain upon them, the more they feel he is one of them deep down and the more they seek his approval, getting even more disdain in the process. He actually cannot stand teaching the classes that he does but it pays the bills and so he does it,
He is good at teaching art because he has an actual passion for art. He is an avid connoisseur of art, spending all of his available money to acquire exotic works of art for his own pleasure.
He once had almost as much passion for mountain climbing and was considered one of the best in that extremely cliquish sport. Time has taken some of the pleasure, and ability, out of him and since its cost collided with his other love, one had to give.
Hemlock has one other vocation that brings in even more money than his teaching; he works for CII, a counter-assassination secret governmental organization run by a bizarre albino named Dragon. Under the direction of this man to whom natural sunlight or any bright light at all is extremely painful, CII performs a highly covert duty that the other intelligence agencies need but do not want to handle. It takes care of sanctions, the euphemism for killing the killers of U.S. agents.
As the series begins, two events collide to cause Hemlock trouble. The first is his decision to resign from CII effective immediately. He has tired of the killing and tired of the danger and feels his art collection is fine the way it is. The second is the murder of a CII agent. Dragon knows that the aggression against his own agency must be punished and for that he wants only the best, namely Hemlock.
Since Hemlock is not interested in the money and Dragon desperately needs Hemlock, the pressure begins.