Sleeper Code -- Part I in the Sleeper Conspiracy -- Tom Sniegoski

Tom Lovett is a narcoleptic.  That's hard enough.  Even worse, he suffers from a rare strain of narcolepsy that can cause him to lose entire days at a time.  Life stinks, but he's pretty used to it.

Then his whole world changes.  He discovers that his body isn't actually sleeping during the episodes -- only his personality is:  While he is sleeping, his second personality -- a highly trained, government-created cold-blooded assassin takes over.

While I wasn't particularly impressed by the writing:

Mason anticipated the sensation that was to follow his thrust, the vibration that would travel up through the metal of the blade, into the handle, and into his arm--the feeling of flesh pierced and the razor-sharp edge of a blade grazing across bone as the point of the weapon sought the pulsing muscular organ behind the rib cage that was the human heart.

I found myself drawn into the plot.  It did bother me that it was so totally, TOTALLY obvious that his parents weren't his parents but that Tom, supposedly a smart guy, didn't realize it until it was almost too late. 

Okay:  Say his parents are innocent, that they are unaware of his true situation.  If he's asleep for five days, but actually isn't asleep and is actually out assassinating people, don't you think his parents would have noticed that something wasn't quite right?  My suspension of disbelief only goes so far. 

Regardless of my issues, I do think that fans of the Alex Rider series, Mission Impossible and especially the Bourne movies will enjoy.