The Mary Louise Series is a collection of four novels concerned with adolescent girl detectives written under the pseudonym Edith Van Dyne. The series began with Mary Louise, originally written as a tribute to Baum's favorite sister, Mary Louise Baum Brewster. She is a fifteen-year-old girl with unusual maturity (though the other girls in her boarding school find her somewhat priggish). She is suddenly confronted with the fact that her beloved grandfather...