The Case of the Missing Tree: Mo's Elementary Mysteries, Book Five (Unabridged‪)‬

While Kayla and Kimberly are out of town for a gymnastics competition, Monique is left to hang out with Peter and Paul. While skateboarding at the park on a Saturday afternoon, they remember they could earn extra credit for assisting with planting as part of the Arbor Day weekend. During their volunteer efforts, they discover one of the trees has gone missing. It's up to Mo, Peter, and Paul to figure out what happened and why.