Mary Louise and the Liberty Gi

The books are concerned with adolescent girl detectives

The books are concerned with adolescent girl detectives — a concept Baum had experimented with earlier, in The Daring Twins (1911) and Phoebe Daring (1912). The Bluebird series began with Mary Louise, originally written as a tribute to Baum's favorite sister, Mary Louise Baum Brewster. Baum's publisher, Reilly & Britton, rejected that manuscript, apparently judging the heroine too independent. Baum wrote a new version of the book; the original manuscript is lost.

The title character is Mary Louise Burrows. In the first books of the series, 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 is suspected of no less a crime than treason against the United States. With the help of old and new friends of Mary Louise, her grandfather's innocence is revealed and the truth is uncovered. The novel features a federal agent named John O'Gorman; he is assisted by his daughter Josie, a young woman he has himself trained to function as an investigator. (The Josie O'Gorman character, despite preceding Nancy Drew by more than a decade, is much less traditionally feminine.) Subsequent novels in the series ring changes on this basic formula. The second book, Mary Louise in the Country, involves the struggle for Irish independence from Britain. Josie O'Gorman, tougher and less ladylike than Mary Louise, has a more prominent role, and eventually she takes over the series. Sampson eventually relented and named the last few books after this character.