 The Hardy boys, their father, and their friend Chet Morton fly to Mexico where they find a band of Indians and a strange oil smuggling operation using submarines.Their deductions lead them to a small Mexican town where they learn that local people are mysteriously disappearing and the strange crest appears on the doors of people who have disappeared.The Hardys find a local youth by the name of Tico who is a great navigator and helps the Hardy boys find the culprit's hideout where they learn the real man behind the scheme is Cardillo, who is called "Pavura", which means terror in Spanish, by the Indians.