I just finished reading Sapphique by Catherine Fisher. It's the second and final book following Incarceron. They're a unique take on distopian fiction. Incarceron is a prison that is alive and has the power to care for or torment its prisoners. The outside world appears to be a medieval kingdom, but they have advanced technology and have chosen to not use it -- or so it appears.
They live in a very unique castle. Here is the opening line: "Whenever Castle Glower became bored, it would grow a new room or two." The plot thickens (rising action) when their parents go missing and are apparently dead. A wicked foreign prince and traitorous counselors from their own government plot to take over the country, underestimating the three royal children and the powers of the castle itself.
I just realized that Sapphique and Tuesdays at the Castle share a common idea -- a building that lives and thinks. However that two books have very different moods and outcomes.
Sapphique is distopian fiction, and Tuesdays at the Castle is fantasy.