Mr. Quisling is definitely up to something mysterious, and Emily and James are on high alert. First, there's the coded note he drops at a book event. Then Emily and James uncover a trail of encrypted messages in books by Mark Twain hidden through Book Scavenger. What is most suspicious is that each hidden book triggers an arson.

Mystery ranch: The Alden's visit their mysterious Aunt Jane at her run-down ranch and make a surprising discovery! Mike's mystery : A nearby house burns down while the Boxcar Children are staying with their Aunt Jane and their friend Mike is blamed for starting the fire! Blue Bay mystery : The Alden's are excited to visit a deserted South Seas island. But soon they discover clues that they are not alone. Is someone on the island watching them?