Cherringham-The Last Puzzle by Matthew Costello and Neil Richards
Another Jack and Sarah mystery. A man that wrote crossword puzzles for the New York Post and a friend of Sarah's father Michael was found dead by Michael when he went to his friends house for their weekly game of chess. His will stipulates that Jack and Sarah are to watch his heirs while they try to solve a crossword puzzle to win his millions.
I received this in return for an honest review!