In a far distant future when the Sun is dying + the Earth along with it, a journeyman torturer disgraces his guild and is banished to a distant town to serve as a headsman. The text is ostensibly a translation of his recovered memoir in which he recounts his travels.
It’s a masterful puzzle box that rewards an attentive reader. The protagonist is an annoying liar (I personally found this a challenging and engaging thing about the text). I highly recommend Ada Palmer’s introduction, if you can find that particular edition.
This is the book that got me back into sci-fi but it’s not a particularly casual read.