Iain M. Banks' Inversions is a covert Culture novel. Set on a quasi-medieval world, two of the characters are secretly from the technologically advanced Culture in which most of his other SF novels are set. They conceal their origins, but the clues are there.
The book is both artful and subtle. Like Lewis Carrol's Through the Looking Glass, inversions are a recurring theme. A mirror image is a reversed image. Like Carrol, Banks uses a game very like chess as an extended metaphor. The story is set in two opposed nations, told in alternating chapters. Like the pieces of a game of chess, we see symmetrical but opposite figures on both sides. In Haspidus, a king rules, in Tassesen a republican usurper. In Haspidus the king is assisted by the merciful and skilled Dr. Vossil, in Tassesen, the Protector is protected by an efficient black-clad assassin of assassins, of obscure origins, DeWar. Kindly Dr. Vossil leaves a trail of corpses in her wake, and the grim DeWar reveals a remarkably soft heart.
Banks rings the changes on inversion throughout the book: when must you be cruel to be kind? And look for how often a figure in the Haspidus narrative has an inverted counterpart in Tassasen.
Both of the parallel tales are told by unreliable narrators, and I think that is another theme of the book. Neither narrator knows more of the story than what they know from personal knowledge, so they are missing some important information that the reader knows, and they are reticent in sharing what they do know.
The teller of the Tassesen narrative explicitly hides their identity. Consider who could know the story they tell, personally or from reliable informants they would know.
This is one of my favorite Banks.