As you can tell from my introduction, the investigation leads Falcon in a number of different directions. It involves the American and Spanish secret services, and Falcon's Muslim and Arabic friends. It also see Falcon develop a love interest, and a married couple have a rather sordid set of goings on (for no apparent reason that really advanced the story, so far as I could tell).
The different strands are all woven together rather neatly by the end. The problem is it took a while to get there. Don't get me wrong, I mostly liked the journey, but did we really need the love interest? Probably not. Did we need the married couple's sordid goings on? Not really, and I rather suspect that the book would have been tighter for them not being there.