John Ruddock (Mr. Wilson)Richard Palmer (John Adams)Hilda Fenemore (Mrs. Adams)Harry Pettit (Father)Mrs. Harry Pettit Sr. (Mother)Merrilyn Pettit (Merrilyn)Hilary Pettit (Hilary)Harry Pettit Jr. (Harry)
14-year-old John Adams lives with his mother, who works as a cleaning lady. During holiday time, when he isn't helping his mother's employer Mr. Wilson, an elderly antique dealer, put his books in order, he strolls along the pond on the banks of which stands a charming old mill. This year Mrs. Adams has shown John a casket containing a parchment indicating that a treasure has been buried at the mill. John dreams of finding the treasure and buying his deserving mother a cottage. He will have help from Merrilyn (16), Hilary(14), and Harry (10), the children of the owners of an estate by the pond; but his plans might be thwarted by Mr. Wilson, who will show his true colors: greed and spite.