The Codex was an enjoyable adventure of survival through the jungles of Honduras. The author, Douglas Preston, certainly put his characters through everything imaginable during their travels. Not many surprises as far as plot goes, and yet the climax was still pretty exciting. Not bad for something to listen to on your commute.
SPOILER ALERT! Read no further if you want to remain free of any knowledge of the story.
The main disappointment I had with The Codex was with the character of Sally. In an effort to create a character that was combative and strong, Preston made Sally stereotypically feminist beyond what I found believable, given that her character's role as an "ethno-pharmacologist." Through her work, she had to have encountered people of many cultures, and if she had not accepted the differences among them, she certainly would have had to acknowledge them. And yet she acted so insulted when the old man from the jungles of Honduras displayed views of women typical for his traditional culture. His comments were usually made in fun, but she always became terribly insulted. I found it a bit ridiculous. Yes, perhaps at 29, she's still young enough (yes, that's young!) to be a bit idealistic. But it came across more of an ignorance of where the man was coming from. I didn't find her hostility believable.