They Do It With Mirrors // Murder With Mirrors — Agatha Christie

Responding to her friend Carrie's urgent invitation, Miss Jane Marple has arrived at her sprawling estate. To Miss Marple's surprise, Carrie's remote "Gothic monstrosity" has been turned into a home for delinquent boys. What's more, Carrie's own children and grandchildren have taken up residence--and few of them are thrilled at how mother is squandering the family fortune. Then a brutal murder proves that philanthropy is the least of Carrie's problems--and Miss Marple finds that where there's smoke, there's mirrors.