Mona is a five-year-old girl who loves to solve mysteries. In this book, she wants to explore the question of where all her father's socks went. However, to do that, she must face her fears and explore her house to locate the missing socks. Mona believes that a monster must have eaten her father's socks because she does not believe that socks can go missing on their own. With only a short window of time to solve the mystery, Mona is ready to take on the task. She is not given a lot of clues and must rely on her knowledge of mystery solving. She is faced with a lot of challenges as she goes on her journey to find her father's missing socks. With hard work and dedication, Mona is able to solve the mystery and tell her dad where all his socks went.