The old mill had been abandoned for years, but one day, a small group of children stumbled upon it while exploring the nearby pond. As they wandered through the grim, dusty halls, they came across a curious sight – a single, plump plum sitting on a shelf, untouched and seemingly out of place.

The children couldn't resist the temptation to investigate. They gathered around the shelf, examining the plum closely. One of them, a girl with a keen eye, noticed a faint hint of a plot on the fruit's surface. Intrigued, the children began to search the mill, looking for any clues that might explain the mysterious plum.

As they scoured the building, they discovered a heavy cash box hidden in a flat drawer, its contents untouched. The children's excitement grew, and they wondered if the plum and the cash box were somehow connected. They decided to call the local authorities, but before they could, a strange figure appeared – a grim-faced man who had been watching them from the bluff outside.

The children froze, unsure of what to do. The man approached them, his steps heavy and ominous. But to their surprise, he simply gestured to the plum and said, "That plum holds the key to a great wealth. I've been searching for it for years." The children listened, their eyes wide with wonder, as the man explained that the plum was a clue to the location of a hidden fortune that had been lost for decades.

Intrigued, the children agreed to help the man solve the mystery, and together they set out to uncover the secrets of the abandoned mill and the plum on the shelf. As they worked, they realized that they were part of a grand adventure, one that would test their wits and their courage, and perhaps even lead them to a life-changing discovery.