Passport to Danger is a Nancy Drew and Hardy Boys Supermystery crossover novel. It is the 19th book in the series and was first published in July 1994 by Archway Paperbacks.[1]
In the story, Nancy heads to San Miguel de Allende, Mexico, a small town where the Obermans, a couple running an art school, suspect a plan involving counterfeit visas being used to smuggle Mexican citizens into the U.S. Meanwhile, the Hardys must retrieve a priceless mask from an art thief in Mexico City, and return it to a local family's art museum. Nancy and the boys must find a connection, and solve the mystery.