I recently read two books by Pat Walsh. They're the Crowfield Curse and The Crowfield Demon and both are scary and exciting.
The books take place in the 1300s and the main character is an orphan boy, William, who works at a monastery for his room and board. He's someone we quickly learn to care about.
Both books include a lot of supernatural stuff about demons and might be too scary for some kids. But there are also angels involved and each one has a satisfying conclusion while leaving the reader wanting more. I assume there another book in the series will be published in the future.
One thing I enjoyed about these books is the way the author managed to make the fictional, fantasy setting show a realistic portrayal of what life in a monastery during that time period must really have been like. Combining accuracy and imagination is an impressive feat.
Anyone who enjoys fantasy and historical fiction will enjoy these books.