L. Frank Baum is best known for whisking us away to the Emerald City, but in his later years, he created a very different kind of heroine: Mary Louise Burrows. This book catches up with her after her earlier adventures, showing us a more mature and determined young woman.

The Story

Mary Louise lives a happy, quiet life with her adored grandfather, Colonel Weatherby. Everything changes overnight. First, her grandfather disappears without a word. Then, federal agents arrive, accusing him of being a dangerous spy. Mary Louise is shattered. She refuses to believe the man who raised her could be a traitor. Convinced he's in trouble or hiding for a good reason, she decides to find him herself. Her search pulls her into a web of coded messages, suspicious strangers, and hidden motives. With the help of her loyal friends, she follows a faint trail, facing danger and doubt at every turn, all while battling the public shame of the accusations against her family.

Why You Should Read It

What I love about this book is its heart. It’s not just a cold puzzle. At its core, it's about faith. Mary Louise’s belief in her grandfather is unshakable, and that personal mission drives the whole mystery. Baum writes her as smart and resourceful, but also vulnerable. You feel her fear and frustration. It’s also a fascinating look at a post-WWI America paranoid about spies, which adds real tension. The mystery itself is fun—it has those classic, clue-driven moments where you try to piece things together alongside Mary Louise.

Final Verdict

This book is perfect for anyone who enjoys classic mysteries from the early 1900s, like the Nancy Drew or Hardy Boys series, but wants a story with a bit more emotional weight. It’s also a must-try for Baum completists curious to see his talent outside of Oz. If you're looking for a fast-paced, wholesome mystery about loyalty, family, and a clever girl out to prove the world wrong, Mary Louise has a case for you.