Does anybody remember this book?

The main character's name was Kate. Hero's name was Christopher. The era was during the Elizabethan era. It was some sort of fantasy historical romance. I think YA or Children's. There were some pictures.

Basically, the main character gets shipped over to a manor because of something or other, I can't remember. While there, she meets a young man named Christopher. They promptly dislike each other. Somehow he gets captured by the fairy people that live underneath the manor, and she ends up going down to save him...

I was looking for it in the library, but I don't remember the author or the title. The title had something to do with the name of the house.

ETA: Nevermind, found that it's called "The Perilous Gard"