The Ghost Parade
Judy is going to a camp. The school she went to had burned down so the students were going to get a long summer vacation. Irene is also going. Judy is currently 15 years old. The camp is called the 1000 island camp.
There are two plots going. One involves a counterfeiting group that was making fake $10 bills (this was 1933 so $10 meant a lot more then.)
In the other are all the things that involve the camp. Judy buys 7 wooden Indian heads at an auction and then finds out that they are supposedly cursed. (The Pequod War, or Pequot War, took place from 1834 until 1938.)
Problems start to arise at the camp which some people think are due to the curse of the wooden heads. The heads seem to move in their storage box, there's a problem with a snake, a girl is cut by a cat and so on.
Then, to top it all, all seven heads go missing. It turns out to be two mysteries and they keep Judy quite busy. A good story.