The Mark on the Door by Franklin W. Dixon, the 13th book in the Hardy Boys series published in 1934, involves a mystery that starts locally and quickly takes Frank and Joe Hardy to Mexico. 

The plot begins when Frank and Joe are almost hit by a speeding car and later link the same driver to a theft from their friend, Chet Morton. Investigating, they find a ring with a strange insignia, described as a flaming bundle of sticks with a superimposed letter "P". They also receive a threatening note saying "BEWARE OF THE MARK ON THE DOOR!". 

These clues connect to their father, Fenton Hardy's case involving a missing bookkeeper due to testify against a Mexican company selling fraudulent stock. The Hardys and Chet travel to Mexico, where they encounter a community facing mysterious disappearances and a powerful criminal known as Pavura (meaning "terror"). They discover that the strange crest from the ring appears on the doors of the missing individuals. 

With the help of a local guide, they uncover an oil smuggling operation using submarines. The investigation reveals that Pavura is the mastermind behind both the disappearances and the smuggling. The book culminates with the Hardys and Chet stopping the smugglers and solving the linked mysteries.