Cecil and Winifred Percival
Cecil and Winifred Percival are relatives who come looking for the loot when it is announced that Dingo Towne has left his fortune to whoever can find it first. While they are greedy criminals, they unfortuantely do not have the brainpower to solve the riddles and must therefore rely on trying to follow the boys and close in on the treasure when the boys discover it. The Percivals threaten the boys on several occasions, once at the Jones Salvage Yard when Aunt Mathilda is forced to intervene. However, they prove to be no match for the boys, who eventually solve the riddles and locate the missing loot.