So why was Ezra Fier in shock at the end of the last chapter? What could be so amazing that there was a burst of emotion from him? It's because he spent all that effort to be greeted by a wall made of stone!
Ezra is both shocked and annoyed as the entire study has been walled in. Maybe Constance was afraid of what Matthew had become? Maybe Matthew walled himself in because of madness? Maybe a bunch of things.