Book cover art.
The Moonstone Castle Mystery is the fortieth volume in the Nancy Drew Mystery Stories series.
Plot
When Nancy recieves a valuable moonstone as a gift from an unknown person, she is amazed and puzzled. She soon becomes involved in a mystery involving the Bowens and their missing granddaughter which leads Nancy, Bess and George to Deep River. Investigating the haunted Moonstone Castle leads to a connection between the castle and the mysterious, as well as the revelation of what happened to Joanie Horton.
