Houseboat Mystery

The Boxcar Children #12 Houseboat Mystery by Gertrude Chandler Warner, 1967. Mr. Alden takes his grandchildren on a houseboat trip. It’s a peaceful trip at first, but they keep having encounters with someone driving a black car recklessly. It seems like the car turns up every place they go. Then, Mr. Alden takes the children to an auction because Violet and Benny have never seen an auction before. They think it’s really interesting, but the auction is cut short because a valuable vase has been stolen. The police say it’s just part of a string of thefts that have been going on in the area. After that, they visit a place called April Center, which is owned by an old friend of Mr. Alden. It’s a sort of mock town/park/tourist center. Cars aren’t allowed inside, so people rent horse-drawn carriages to go around the place and see various attractions. However, Mr. Alden and the kids notice that the horse that draws their carriage looks unusually thin, like it hasn’t been fed well. Mr. Alden…