PenthousePenrod and Sam spring into action after a member of their junior G Men Club loses his mother in a bank shoot out. Since the club is pledged to solve crimes and bring crooks to justice, the boys set out to capture the killers but are instead captured when the killers hide out in their clubhouse. After Penrod's rival, Rodney, is also captured, the three boys join forces to hatch a daring plot and outsmart their captors.