At Hartington Manor, Lady Osbaldestone is enjoying the company of her intrepid grandchildren when they are joined by the children's favorite uncle, Christopher, who is seeking refuge, for he is a master intelligencer who was being tailed, not only by a French agent but also by a London lady with matrimonial intent. Determined to avoid her, he enlists the children's help to find out what she is up to, and as they join in the village events, they do their best to learn about Miss Marion Sewell.