Fred is driving the Mystery Machine along I-35 in San Antonio. Once the Mystery Machine gets off the freeway, it is on to the hotel near the RiverWalk where Mystery, Inc. is staying at. At the hotel, they meet some other guests who are also mystery solvers. Their names are Skip Gilroy, April Stewart, and Augie Anderson. Also with them is their dog Elmo. Shaggy and Scooby-Doo are spooked when they see two ghosts who turn out to be friends of Skip, April, Augie, and Elmo. The human ghost introduces himself as the Ghost of Jonathan Wellington Muddlemore but asks that he be called Mudsy. He also introduces his cat Boo. All of the mystery solvers are going to see the Alamo. When they arrive at the Alamo, however, they discover that it is supposedly haunted by the Ghost of Davy Crockett. Mudsy finds out that Davy Crockett was a soldier who fought in the Texas Revolution in 1836, sixty years after his death, and died defending the Alamo from the Mexicans. Mudsy might just be the person his friends need to scare this ghost into revealing himself a phony.