A body in the library - Agatha Christie

At seven in the morning, Colonel Pantree and his wife woke up to find the body of a girl lying on the carpet in front of the fireplace in the library room! Who is she? How did she get to their library? And what is her connection to the other girl whose burned body was found inside a car nearby? Mrs. Pantree finds no one to help her except her close friend, Miss Marble, so how will the old spinster succeed in solving this intriguing mystery? Number of pages: 267