It is June 2006 in St. John, a town in Northwest Indiana, and five siblings find out about the existence of dinosaurs through their neighbors who actually visited them. At a swimming party, the neighbors give the three younger siblings a book with a T-Rex's number on it. When all five kids visit Galavanti Island, they help Dacston, a T-Rex, Valpatic, a velociraptor, Jokie, a brachiosaurus, and Sammy, a stegosaurus, locate a case of saxophones that Selfish Arnie, Dacston's cousin, has taken from all of the citizens of Galavanti Island.