"The Rival Campers Ashore" follows the adventures of a group of young campers who find themselves embroiled in a mystery while spending time near a mysterious old mill. The story begins with the campers, led by the protagonist Roy Blakely, arriving at their campsite for a summer vacation filled with outdoor activities and exploration.However, their plans for a peaceful vacation are disrupted when they stumble upon a series of strange occurrences surrounding the nearby mill. Rumors abound about the mill being haunted, and the campers soon find themselves drawn into a web of intrigue and danger as they attempt to unravel the mystery.As they investigate further, Roy and his friends encounter suspicious characters, hidden passages, and unexpected twists and turns. Along the way, they must use their wits, bravery, and teamwork to uncover the truth behind the mystery of the mill and put an end to the sinister activities taking place in their midst.