Two adversaries are forced to live together in a labyrinth-like castle and have to solve puzzles. Their countries are at war, and they are isolated in a place without anything outside of it. How do they cope? What do they achieve? What the hell are they there for? Who is going to help them? Are they ever going to get out? Is this Science Fiction? No. Is this Dungeons and dragons? No. Is this literature? Maybe. You decide. Is it compelling? Yes. Banks is a master in visualising worlds and you just have to go along with these individuals to find out what they themselves find out.