“The River Motor Boat Boys on the Colorado; Or, The Clue in the Rocks” by Harry Gordon promises another riveting installment in the series. Join the River Motor Boat Boys as they explore the challenging waters of the Colorado River and stumble upon a perplexing clue hidden in the rocks. Gordon's talent for blending adventure and mystery ensures that readers will be hooked from beginning to end, making this a perfect addition to the series for those seeking excitement and intrigue.