借鏡殺人 

Marple is invited to London to see her old friend Ruth. Miss Marple was a sort of traveling companion to Ruth and her sister, Carrie Louise. Ruth is worried about Carrie Louise. She doesn't know why, though. Ruth asks Miss Marple to come with her to her sister's estate, Stonygates. Stonygates is a huge manor house, and some of the buildings and the grounds are used by Carrie Lo...