Peter is an imaginative fourth grader who is grieving the loss of his father in the First World War. As he prepares to leave school for summer vacation, Peter distracts himself from his sadness by daydreaming about all the fun he is going to have in the treehouse his uncle is building for him in the backyard of his home in Lavender Valley. But little does he know that his mom, Melissa, has a surprise in store for him. When Peter learns his cousin, Jonathan, will be visiting all summer, he can hardly contain his excitement. After the boys reunite at the train station, Peter encounters a stray dog that he quickly adopts. While he continues building relationships with his next-door neighbor, family members, and others in the supportive community of Lavender Valley, everything soon changes when Peter and Jonathan find an old, dusty box in the attic that leads them on an unexpected adventure full of surprises. In his exciting juvenile novel, a fourth grader on summer vacation unearths a box in his attic that contains family secrets and a mystery that begs to be solved.