The Opening Door — Helen Reilly

The Opening Door, first published in 1943 by author Helen Reilly, is a murder-mystery featuring New York City police inspector Christopher McKee, who is called in to solve the puzzling death of a young socialite. From the book cover: “This is the story of a beautiful and haunted young woman. When she was one year old, she was worth nine hundred thousand dollars. At twenty-one, she was sole heir to five million. Before she was twenty-two, she had endured more heartache, greed and violence than her whole estate was worth. It was anybody's guess whether she would ever see twenty-three....”