Fourteen-year-old John Adams lives alone with his mother, who works as a cleaning lady for a living. It's holiday time now. John shares his free time between two activities, helping Mr. Wilson, an old antique dealer who is also his mother's employer, to put his books in order and strolling along the pond on the banks of which stands a charming old mill. Now, Mrs Adams has shown John a casket containing a parchment indicating that a treasure has been buried at the mill. The boy has a dream : finding the treasure and buying his deserving mother a cottage. To this end he will be helped by Merrilyn(16), Hilary(14) and Harry(10), the children of the new owners of an estate by the pond.