Tree House Mystery

Four brave siblings were searching for a home – and found a life of adventure! Join the Boxcar Children as they investigate the mystery of a secret window in this illustrated chapter book series beloved by generations of readers.A family moves into the house next door! The Boxcar Children decide to make friends with their new neighbors by building a tree house with them. In the process, they notice a window in their neighbor's house that nobody knows about. Does the old home have a secret?What started as a single story about the Alden Children has delighted readers for generations and sold more than 80 million books worldwide. Featuring timeless adventures, mystery, and suspense, The Boxcar Children® series continues to inspire children to learn, question, imagine, and grow.