Outstanding - I can't rate this highly enough.
The characters live in an alternative Tudor England, where warring countries are supported by armies of 'Deepsmen' - a race of underwater dwellers.
This summary hardly does justice to the power of the book - it's about warring ideologies, about religion and philosophy, about what it means to experience the world. The intelligence and learning of the author is clear throughout - and yet the book is a gripping read from start to finish.
If you loved Wolf Hall, I highly recommend this book.