While Dr. Grease is inspecting an old steam locomotive, it takes off by itself down the track. Biggie D, Boone, Fleming, and Himari have to band together in order to overcome obstacles to get ahead of the runaway train and bring it to a stop. / New members Curl, Gonzales, and Layla get introduced and the Paq befriend them. While Bates, Himari, and Klaus are spending time with the new members, they find it difficult to relate to the new cars. The Paq must put aside their differences and work together in order to save Shaq from danger.