The Mark of the Assassin by Daniel Silva

When Michael Osborne of the CIA is called in to investigate the terrorist bombing of an airliner off the coast of Long Island, there is one relevant clue that drives him:  A body found in the water, near the crash site, with three bullet holes to its face.  Osborne recognizes the deadly markings as the work of a world class assassin a man whose very existence has never been proven because the only people ever to have seen him becamse his victims.  Among those victims:  A young woman Osborne loved years before. 

As Osborne gets closer and closer to solving the puzzle of the airline crase his personal obsessions threaten to consume not only the investigation, but his marriage and family life as well.  And when the frightening identity of the assassin's employers becomes clear Osborne puts himself, and his loved ones, into the sights of the most fearsome man on earth. 

If you are looking for an action adventure book with good characters and plot twists, you might enjoy this book.