Set on the frozen planet Mesklin, its disc-shape formed by its crushing gravity, this story is narrated partly by a human inside comprehensive safety gear, and partly by one of the 15 inch long creatures who've evolved there. The humans have lost something, and are trying to work with the Mesklinites to find it. Complexities ensue. I enjoyed the alien POV most, especially the detail around not being able to imagine projectile weapons -- anything thrown would hit the ground a nano-second later due to the gravity -- and having a deep, rational fear of falling any distance at all, for the same reason. However, this is also a fluffy book in some ways, and change happens rather more smoothly and conveniently than it would be if written today. Fifties sci-fi really just got on with the story! However, it's a fun, short read; recommended to anyone who'd like to try hard science fiction, without committing to a 600 page "physics textbook with plot."