42. Deathworld 2 by Harry Harrison

Deathworld 2 reminds me of why I enjoyed Harrison's work so much when I was a teenage nerd.  His books are somewhat simple and straightforward with a relentless narrative.  You get the smattering of theory and nerdy superiority but it is wrapped up in a story that has constant discovery around the corner.  You keep turning the pages because you want to discover the world Jason dinAlt is making his way through as well as to see what happens to him (or more accurately how he bests the situation with his superior rationality).

In the second book, he is immediately kidnapped from Pyrran by Mikah, a self-righteous activist from the planet where Jason won the money that started his trip to Deathworld.  Mikah is a caricature of the puritan.  He represents a minority group that wants to stop the gambling on his homeworld by putting Jason on trial and exposing the fraud of the gambling syndicates who are using him for advertising (because he won so much money).  Jason breaks free and sabotages the ship and they crash on a super-primitive slave world.  They get caught by a slaver whose sole existence is walking a group of slaves back and forth through the desert, digging up these roots for food.  The rest of the narrative is Jason making his way up the food chain, first by might and then later by his knowledge of technology.  He ends up as the main advisor to the tribe that controls a very primitive form of electricity.  His goal is to find a space port and failing that, signalling into space in the hopes of getting rescued.  There is a lot of fun as he impresses the tribes with his knowledge, fights a lot and keeps not killing Mikah who keeps self-righteously ratting him out.

Underneath the fun are themes of technology and transparency of ideas, puritanism vs. relativism and morality.  Sometimes it is a bit heavy handed, which was the norm for sci fi of these times.  The primitive society's biggest flaw is that they hide their technology from each other and the most annoying character is rigid Mikah.  It's all writ fairly obviously but its okay because there is so much fun along the way.