Hitman is a collection of short stories about a professional killer named Keller. What sets this book apart from others of its kind is that it's more about what Keller does when he's not actively killing people, what makes him tick. He has fantasies about living in whatever town he's visiting for a job. He has a dog that he's quite attached to. And eventually he takes up stamp collecting as a hobby so he'll have something to do when he retires.
That's not to say there's no action. Keller dispatches quite a few people in this book. He's a professional and the ways he figures out how to pull off the killings are well done.
Lawrence Block's writing is another attraction for picking this up. He knows how to weave a short story like nobody's business. There isn't a single dud in the collection as far as I'm concerned.
If hitmen interest you, go out and get this RIGHT NOW! Keller's a fleshed out character and a joy to read about. I'll be picking up the other two Keller books in short order.