Cole Sudden is an agent with the CIA.
In fact, he is an assassin for them. Not officially, of course, because officially the Agency does not conduct such activities any longer. Termination with extreme prejudice is a no-no so no one does it.
Except people like Sudden who operates very quietly and removes the people he is told to remove with considerable forethought and finesse. Usually those eliminated are looked at as having died from natural causes like heart attacks or the result of unfortunate accidents like falls down a set of stairs. Being as meticulous as is needed helps Sudden come, take care of business, and then leave with little or no wake.
Cole Sudden is also Cole Swift, a well respected author of thrillers that have sold well and made a modest name for himself though he has not hit the big time yet. His novels of suspense and murder have shown a talent for originality and superb planning resulting in excellent surprise endings.