I just finished reading Susanna Clarke's latest novel, Piranesi. I adored her earlier "Jonathan Strange & Mr Norrell" and "Ladies of Grace Adieu". She popped up in a recent missive from Failbetter Games, noting that the staff there had enjoyed reading this book. In an odd bit of synchronicity, Pirenesi is also the name of one of the ports in Failbetter Games' most recent game Sunless Skies. The two Piranesis don't seem to have influenced one another at all, but both of them draw on an older inspiration from large, mysterious, labyrinthine structures.
Piranesi has basically nothing to do with Clarke's earlier work. I suppose it's possible that it's set in the same alternate reality, but there aren't (to my recollection) any references shared between them. The voice is also completely different. JS&MR had a wonderful Austen-esque impersonal narrator, while Piranesi's first-person narrator has a very specific Voice and a unique Way of Speaking that communicates his particular Character and Way of Thinking.
Piranesi is written as a series of journal entries, and through them we come to learn about the titular character and the world he inhabits: deeply strange to us, deeply comforting and meaningful to him. They are the Halls: a vast, perhaps endless, but varied and distinct series of rooms, connected by doorways and stairways. The Lower Halls are usually submerged, depending on the level of the tides: they bring in fish and seaweed that provide food. The Upper Halls feature windows that open to the sky; when it rains, fresh water pours in. The Middle Halls lie between the two and are the most temperate and livable area, filled with birds and other living things. All of the halls are filled with statues: enormous, towering things, depicting people and animals in a variety of poses and scenes. Piranesi feels a sense of mythical significance towards these, but they're also friendly and familiar connections.
The book unfolds pretty delightfully, and we follow along as Piranesi's worldview is challenged and we learn together about what's really going on: who he is, why he's here, what it all means. The novel starts off very sparse and intimate, with only Piranesi and The Other, but by the end we've gotten to know a dozen or so characters; almost none of them ever actually appear, but we learn about them and their forgotten impact on Piranesi's life.
To recap my own understanding of the situation:
Long ago, there was magic on Earth. There is no magic today; so where did it go? It seeped away into something else. It went somewhere; then it moved on from there. But it left traces of where it had been. An analogy: when it rains, water collects on the surface of the earth, then seeps below the earth, then flows down or out. Over thousands of years, this seepage can create immense caves. When you visit the cave, you won't see any water in there: but everything that you see was created by the now-absent water. Likewise, there isn't any magic in the Halls, but the Halls were created by the magic seeping out of the Earth.
Laurence Arne-Syles, a controversial British professor, theorizes about these spaces and is eventually able to physically visit them. He collects a circle of devoted admirers who share his interest in the occult and mystical. Laurence is deeply unpleasant: intentionally transgressive and perverse, he'll do anything to annoy or hurt others for the fun of it. Along the way he murders and imprisons some who come into his orbit, eventually going to prison for his crimes. (The reality of his accomplishment isn't ever understood or accepted by society as a whole, but they can see the evidence of his victims.)
Laurence moves on to other interests, but one of his erstwhile disciples, Ketterly, wishes to continue. Ketterly captures a doctoral student, Matthew Rose Sorenson, and imprisons him inside the Halls. (As I'm writing this, I realize that the Laurence->Ketterly transition is much like the Earth->Halls or the Magic->Mundane transition. Laurence is no longer present or active in Ketterly's actions, but Ketterly was shaped by Laurence, much like the Halls were shaped by departing magic.) Besides being strange and awe-inspiring, the Halls are also dangerous because, if you spend too much time in them, you'll forget about the world outside. This happens to Matthew, who loses track of his former life, and becomes Piranesi.
The book ends with a lovely, thoughtful epilogue: Matthew is back in the world, still remembering the Halls, and bringing that knowledge with him as he goes about life on Earth. There are some touching moments in the final pages where he sees a person and connects them with a particular Statue in the Halls. The significance of this is unclear: are the Halls reflecting lives on Earth? Predicting it? Is there some higher cosmic truth that is being expressed in different ways on Earth and in the Halls? Piranesi angrily rejects the idea from Raphael that the Statues are "merely" depictions of the "reality" on Earth; from his perspective, the statues are closer to a Platonic ideal, and what we see on Earth is merely an imperfect recreation of the pure expression of the Halls.
Piranesi didn't feel as ambitious as JS&MR, but it's a great book: still dealing with the mixture of the magical and the mundane, this time on a more personal level. It has a wonderful voice and clever (but not cute) structure that guides you on the journey and causes delight as it unfolds a mystery.