This is a sequel to The Second Life of Nick Mason, by Steve Hamilton. That previous book described how Nick was coerced into being the "samurai" (aka, hitman) for imprisoned Chicago crime boss Lucius Cole. Nick is a hitman with scruples, however. He only goes after his designated targets, taking pains to use only non-lethal force on others.
Nick really wants out of this situation. (See the book title.) But until he figures out a way to do that, he has to go along with Cole's current scheme to get out of prison. Which involves (corruptly) forcing a retrial, and having Nick murder the witnesses that testified against him in the original trial. Some returning characters from the previous book, a couple new ones, notably a sociopathic Irish killer who was the previous holder of Nick's current position. And he's pissed at just about everyone.
There's an awful amount of ludicrously-staged mayhem (seemingly written for eventual transition to the big screen) and bad language. Despite the glowing blurbs on the dust jacket, I thought it was pretty perfunctory, but a decent page-turner. Does Nick succeed in his quest to get out from under Cole's thumb and resume a semi-normal life? No spoilers here, but if you look at Steve Hamilton's book list, you'll probably figure that out for yourself.