Meg Mackintosh spends an afternoon at Red Herring Beach with her grandfather. After going for a swim, and after several suspicious characters come in and out of the beach area, Meg's grandfather realizes that his gold watch has gone missing. Meg tackles this mystery with her cousin Maxwell as they search for clues and are led off the track by some red herrings, all adding to the mystery. Clues can be found in the illustrations and questions are posed to the reader to help them solve the case with Meg and Max.