Fardingales

The heroes Humphrey Anthony, his cousin Anstace Rosevere and their friend Tom Vinton (who appear in later books with some of the Chudleighs) find that small articles of personal property mysteriously disappear. There are mysterious passageways and eerie cellars and then Humphrey and Anstace are kidnapped and imprisoned. What has the house Fardingales got to do with desperate criminals?