Frank and Joe Hardy become involved in a case affecting national security when Joe dials a wrong telephone number and gets the Pentagon. Two words- 'Bombay Boomerang'- that the boys hear before the line goes dead plunge them into a whirlpool of danger and intrigue. At the same time, Frank and Joe must save their father from a murderous gang stealing mercury shipments in the Baltimore harbor. With clues linking the mercury thefts to the top secret Super S missile mysteriously stolen from a govern