All aboard for a thrilling mystery on the railway tracks! Henry, Jessie, Violet, and Benny Alden are spending their summer traveling the country in a very special way. They are living inside Caboose Number 777 on the Little North Railroad. Riding at the back of a moving freight train is exciting enough, but the Boxcar Children quickly realize their temporary home is famous. At every single stop, strangers approach the train because they recognize the caboose. It turns out that Number 777 has a wild and unusual past involving an old circus clown and a desperate search for answers. You will need to pay close attention to the tracks ahead as you help the siblings uncover the secrets of the train car. Join the ride and see if you can solve this amazing railway puzzle.