Ah, the Culture novel that some still think isn’t. I feel sorry for anyone who ever read this without knowing about the Culture first. The denouement must be completely mystifying.
The Special Circumstances game applies here, but of course we have absolutely no way of knowing what they’re up to. A Culture agent, alone on a backwards planet (technology at the level of muskets), acting as doctor to a king who’s maybe not quite as bad as some of the other rulers on the planet (or maybe, let’s face it, just as bad).
It’s unusual not to get even the slightest hint of the galaxy-spanning machinations that must be going on behind the scenes, but of course the narrator is a native of the planet and knows nothing about even the existence of other planets.
In some ways it feels like something of an exercise for the author — stunt writing, as Charlie Stross calls it — but luckily the characters are engaging and the stories (there are two running in parallel) are very well told.