"Nancy Drew has traveled to the charming Mexican town of San Miguel de Allende to help Helen and David Oberman avert a disasterous criminal scandal at their prestigous art school. The Obermans have learned that the campus has become a focal point of counterfeiters. Someone is producing bogus green cards, which will be used to exploit and smuggle illegal aliens into the United States.
The Hardy boys have also made their way south to visit the Perelis family in Mexico City. It began as a pleasure trip, but when a priceless Mayan jade mask is stolen from the Perelis art gallery, Frank and Joe get down to business. Discovering an intriguing connection between the theft and the forgers in San Miguel. Nancy and the boys must act quickly to trace the connection to its source--and find the shocking truth behind the ancient mask of mystery."