If you don't know this already, Simple Simon was made into the Bruce Willis movie, Mercury Rising. Unfortunately, in my opinion, the movie doesn't hold a candle to the book - as is the case most of the time a novel is changed for the big screen. If you've seen the movie, don't let that deter you from reading the book. There are enough major differences (more than I can count right now) to keep the reading of this novel fresh and suspenseful...
If you don't know the story, there are plenty of reviews that will reveal it for you, but I'm just going to point out what I liked without giving anything else away.
The main character, Art Jefferson, is a guy you can't help liking. His tenderness towards the autistic Simon is more than touching, and the relationship with his wife (yes, in the book he is married) helps make him more of a real person than the gung-ho, punch-my-boss-in-the-face, tough guy character played by Willis. I didn't know that there were three previous Art Jefferson books and, once I figured it out, I got the impression that the character would be even more engrossing once his previous experiences and relationships with other characters were taken into consideration. Those books, Cloud Burst, October's Ghost, and Capital Punishment are now on my read list to be sure.
The side of the story that deals with "Simple Simon", the autistic boy that has unknowingly cracked an ultra-secret NSA code named KIWI (Mercury in the movie, though before I watched the movie again, I thought the title just meant "Things Are Heating Up!") is very emotional. Without given anything away, there were parts in the book where my heart just broke for Simon, and all autistic children for that matter. Pearson does a great job at making that portion of the story very human.
There's also the matter of a certain character that didn't make the film, a bad guy...er...girl, that added something quite twisted and dark to the story, making it even more emotional and gripping.
The whole NSA side of the story was great, making it the techno-thriller it is and topping it off with a twist of government conspiracy so believable that it may leave you uncomfortable next time you watch C-Span or read about certain clandestine operations and DoD budgets...
How Art ends up protecting Simon is much more believable and less Die Hard 2 than the movie. Everything fits together beautifully, from the FBI to the dark corners of the NSA, from Simon to the sadistic third-party killer after him, from Autism to super codes, and everything in between. This was a great read. Dark, emotional, suspenseful, scary, and... worth reading to be sure.