Here's another book from my childhood that I never forgot (before reading the solution in Wikipedia, consider buying the book used and trying it yourself): http

Here's another book from my childhood that I never forgot (before reading the solution in Wikipedia, consider buying the book used and trying it yourself): https://en.wikipedia.org/wiki/Masquerade_(book) https://en.wikipedia.org/wiki/Masquerade_(book) We used to pore over it for hours trying to figure out anything- noticing certain patterns across the images.