HIT AND RUN, by Lawrence Block, William Morrow, 287 pages, $24.95

Lawrence Block is a legendary mystery writer who has written more than 50 books, his latest being "Hit and Run," the darkly humorous story of a professional hit man who has had a long successful career killing for money without getting caught.

In fact, he has become a millionaire, so when most people would see themselves at midcareer, he decides to retire.

It seems initially the classic illustration that crime does indeed pay, and if you are good at what you do, you will not be punished. Well, maybe not. Out of the blue, he is asked to do one more job, and he hesitates, because his heart is no longer in it. But, hey, what can it hurt to do just one more and then hang it up?

So, Keller accepts the job and travels from his New York home to Des Moines where he is slated to do a final hit — but something goes awry. While waiting for the OK from his client, he plays with his stamp collection when he sees a TV news story that makes him very uncomfortable. An assassin has shot and killed the charismatic governor of Ohio.

It wasn't him! But it is clearly not a good time for his own hit. On the other hand, what if press and law enforcement officials suspect that Keller did it? In fact, within seconds, his face is shown over and over on TV screens, and he knows he is stranded. He is halfway across the country and his ID and credit cards are worthless to him.

His bland, forgettable face is no longer forgettable.

Using an ingenious technique of looking into Keller's mind, Block follows the master criminal as he pulls his head into the shell, constantly worrying about giving even one person the opportunity to see his face, identify him, then call the police.

Of course, he gives up doing his "last job" and starts plotting every move that will get him out of the spotlight and hopefully back to New York. He takes to viewing two movies back-to-back in the daytime. He survives entirely on junk food, purchased at a window with his Homer Simpson cap low over his face. He trades his Sentra for another one.

As the story progresses, the reader easily and quickly identifies with Keller, who seems like such a decent guy. His laid-back but creative personality and finesse grow on you. People who meet him like him, too, except a guy who operates an out-of-the-way gas station who instantly recognizes him and then is instantly dead.

But Keller gets some cash and a credit card out of it so he can travel faster. He starts to take more chances, and when he hears a woman screaming as he walking around New Orleans, he feels compelled to help her. When he saves her life, his future suddenly looks brighter. The woman is so grateful that she invites him into her home (a hit man?), and a new Keller is born.

This is surprisingly crazy, good fun, crafted by an experienced mystery writer who should never put down his pen.

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