Nightkill — F. Paul Wilson

Jack Nacht knows how to take risks and believes in justice, even if it's of the skewed sort. He's one of the best at what he does - and what he does is kill people for a living. But it's a young man's game and he wants out.
His instincts are right. When Jake reluctantly agrees to go on one last hit, he's double-crossed, and ends up completely paralyzed. The mob thinks he's a done deal. But what they don't know is that a brilliant doctor has developed a dangerous and deadly new technique. And if he succeeds, Jake Nacht will not only walk away again - but might also get a shot at revenge.