Scooby-Doo Case Files 1: The Devilish Donut

Scooby-Doo Case Files 1: The Devilish Donut is a children's book published by Scholastic.

Premise
The Mystery Inc. gang have sent Scooby and Shaggy to the gym to get in shape! But a Devilsh giant donut shows up at the gym and threatens to drive away customers.

==Notes/trivia
 * Supposedly, the reader can solve the word and picture puzzles at the end of each chapter to find the suspects and clues they'll need to crack the case.
 * According to reader reviews at Amazon, there are typos in two of the first three puzzles so that they cannot be solved.