Shadow Unit is a different kind of book....it's a tie in set of stories for a TV show that never happened, except in the heads of it's creators.
Think of it as a cross between X-Files, Criminal Minds, Man From UNCLE, etc...more heavily on the Criminal Minds side.
Shadow Unit is a division of the FBI in the Anamolous Crimes Division, investigating the crimes of something they call "gammas", or people that have certain un-explainable powers. They setup and how they go about catching the criminals are straight from Criminal Minds, and that's the closest tie-in.
Each book is a set of short stories with little tie-in extras to give you more insight to the characters (like DVD-Extras).
There are currently 4 seasons of about 8 stories each season that you can read online free, or buy the eBooks. Each "season" does end with a season finale, just like a TV Show. It's obvious that they wanted to make it like a TV Show, and very easy to imagine this in your head as a TV Show.
Bottom line, the first book had 4 stories....the first two were kind of slow, but entertaining...the last two had more of that Criminal Minds flavor that I was looking for. I've heard it continues along that line in the later books, and I've already bought the 2nd one.