Hollywood loves the adventure genre of literature because the stories encompass everything that a good Hollywood blockbuster is all about. There's intrigue and action without all the problems of high production costs associated with science fiction and horror.

Producers get a lot more bang for the their buck translating Jason Bourne and Jack Ryan to the screen then they would Buck Rogers. A single shot in a high budget science fiction movie can cost more than a million dollars. It has all the special effects and CGI graphics that have to be designed and put in post production.

Many times it's just an actor standing in front of a giant green screen. With adventure characters, the special effects tend to be of the explosion variety. The translations also goes both ways. an adventure movie is easy to turn into a small graphic novel or book.

The problem with taking a translation from book to film is you can't fit everything in one movie. Since one minute of a movie roughly translates to one page of a screenplay, which is considerably less than one page of a book, turning a 600 page book into a 100 page screenplay means taking out a lot.

That means entire subplots and characters are removed, so the producers can focus on the main plot. You may watch the Bourne Supremacy on the screen, but it will be radically different than the book you read a year earlier. Adventure stories make great movies, but don't expect the depth and intricacy of the book.