Fourth-grader Jo Schmo discovers a mysterious crate on her doorstep containing a superhero costume and gadgets. Putting it on transforms her into 'Jo Schmo, Crime Fighter,' and she embarks on hilarious adventures to protect her town of San Francisco from comical villains. With the help of her dog, Raymond, and her skeptical but supportive friend, Wyatt, Jo learns that being a hero is about more than just cool gear—it's about using your wits, helping others, and staying true to yourself. The book is a fun, fast-paced mix of everyday school life and over-the-top superhero action.