Arsène Lupin decides to run a detective agency in addition to being a gentleman thief. As a detective he happens to cooperate with police in order to unveil the criminal activities of a villain. When he succeeds the villain returns the favour. The unmasked Arsène Lupin manages to escape with the villain's gangster moll as his new companion.

When one of their number tries to tear away the veil from the face of a woman of Morocco, five French tourists find themselves cursed by an Arabic sorcerer to die in a specified order before the next new moon appears - and one by one, in different ways, they begin to die as predicted...