Keller's Designated Hitter by Lawrence Block

In this gripping tale, a professional hitman finds himself in a moral quandary when his latest assignment takes an unexpected turn. Tasked with eliminating a seemingly ordinary man, the hitman uncovers layers of deception and hidden motives that challenge his own code of ethics. As he navigates the murky waters of loyalty and betrayal, he must decide whether to follow through with the job or risk everything to uncover the truth. This suspenseful narrative explores themes of identity, choice, and the blurred lines between right and wrong.