On the recommendation of a friend, I read The Descent by Jeff Long. This novel concerns the discovery that the Earth is somewhat hollow, and living down there is an entire race of beings whose bodily features are frighteningly similar to those we assign to the classical image of demons. Many myths have some basis in some kind of historical fact; what Long has done here is to try to envision the historical fact that would have given rise to our religious ideas of Hell and its minions.
I found this novel to be one of the more amazing reads I've had in a while, but it took me all the way to the end to make that decision. Along the way, the book moves in a lot of different directions, and the resulting lack of focus is somewhat maddening. Examining the religious implications of such a discovery alone could make for an entire thick novel; so, too, could the story of the intrepid explorers who are sent to explore it. Ditto the war that breaks out briefly between the surface-dwellers and the hadals (the name given to the subterranean race, homo hadalis). Also throw in linguistic theory -- the book's main character is a nun who has spent her life searching for the lost "mother language" -- and Jules Verne homages and the standard not-all-that-benevolent-billionaire who drives most stories like this, and you have one of the densest books, in terms of things that are happening, that I've ever encountered.
All this plot, though, means that characterization takes a back seat. Of all the characters in the book, only two -- maybe three -- are really sharply drawn. The remainder are ciphers, basically filling in obligatory parts that must be played for the plot to work. This overdensity of plot combined with the broad-line characterization combines to make the book hard to really sink one's teeth into.
The book's ending, though, is nothing short of amazing. All of the various plotlines come together in the space of about one hundred twenty pages. This is one of those books where nothing makes sense until the reader is done with the entire work and able to sit back and see how it all fits together. This may be a book that improves on successive readings, when the events in the front portion of the work take on a different light given knowledge of what is to come.
The Descent is by turns horror, adventure novel, love story, philosophical novel, religious novel, and science fiction. It doesn't start out being a page-turner, but it becomes one.