Buddy, Tiny, and Mom visit their very large sauropod friend, Arnie Argentinosaurus, and his dad. Arnie has grown bigger since our kids have seen him and is now too big to ride on the Dinosaur Train anymore. Tiny and Buddy arrange with Mr. Conductor for Arnie to be the first big dinosaur to ride on the newest Dinosaur Train car - the flatbed car! Mr. Pteranodon and Mr. Lambeosaurus take all the kids to see a field of geysers - holes in the ground that hot water shoots out from! At the same time, Mrs. Pteranodon and Mrs. Lambeosaurus are relaxing nearby in soothing pools of warm water, called hot springs. In the end, the kids love seeing the geysers and then joining the Moms in their hot springs, while accidentally surprising Mr. Conductor who is secretly trying to relax in his own private hot spring pool!