John F. D. Taff 
Sorcerer’s Apprentice [EPUB ebook] 

The search for the world’s master assassin begins with a single question…. Would you kill a person if you knew you could get away with it? A simple question. An innocent question? David Benning, a successful accountant, is a man whose answers to life’s questions have lately all been wrong. He has a dying father racking up charges at an expensive nursing home and a bank account with embezzled money sitting in it. When he’s blackmailed by a shadowy organization known only as "The Group, " David finds himself thrust into a world outside his normal boundaries–one involving guns and payoffs and killing unknown, seemingly ordinary people.