When the weather has been extremely dry for several weeks, all the water holes at Pteranodon Terrace dry up. The Lambeosaurus family decides to move away in search of water, which upsets the kids. Dad and Mom decide to take the kids to the Big Pond on a camping trip, where they will wait out the drought and return home when it rains again. Don doesn't want to leave his home, even temporarily, and decides to perfect a "rain dance" that will make the rain return. Dad learns that he's been chosen to compete in the big annual Fishing Contest at the Big Misty Sea, and is one of three contestants. The whole family rides there on the Dinosaur Train to cheer Dad on. They learn that the contestants are Dad, the Old Spinosaurus, and Dad's childhood friend and rival, a huge raptor named Marco Megaraptor. The three all end up fighting over Chester, the legendary biggest fish in the Big Misty Sea.