Evan Smoak (not his real name) was an orphan who was taken in by a covert government program. Only twelve at the time, he was raised to be an assassin, and he's tops in his field. But, on the edge of burnout, he leaves the program. His new career is what he's been trained for, but totally on the side of the angels. Desperate people find him, somehow, and he saves them from whatever peril they're in. Now, he's the one in peril, but he's not sure why. What's going on? No one is better equipped to find out (specialized equipment is everywhere in this book). What I particularly enjoyed is that there are touches of warmth and humor throughout. For example, an elderly neighbor grabs his arm and clutches him - right over a knife wound. A child who lives several floors below sends him messages - by releasing helium balloons with misspelled comments. Most of the secondary characters are given some dimension, like the macho neighbor who is actually a coward, and the Down's Syndrome kidnap victim who tends to her stuffed animal. This is the first book in a series, and I'm looking forward to the next adventure.