Skull Island is a small uninhabited island in the middle of nowhere.  Only a pretty mermaid has been seen dwelling in one of its caverns.  The island is said to contain many treasures.  Many pirates have tried to reach this land in vain, since it is well guarded by an enormous shark.  Captain Cross-Bones and his assistant Silly Sam still keep on trying to get the loot.  Betsy and Rick are two lively kids, keen on adventure.  They longed to go to Skull Island but knew that Captain Cross-Bones would never allow them to accompany him.