A Song of Stone by Iain Banks
Banks has conjured up an intriguing anachronistic setting. In the aftermath of war, knowing that castles are being attacked, the lord of the castle and his lady try to flee. But they are forced to return to their castle by a sadistic lieutenant of one of the many straggling military groups. Almost all aspects of society, such as it is, have become cruel and perverse, and this being Banks, has a particularly strange and nasty ending.
I can recommend it for the many fascinations in context and human failure, but beware, it is bleak.