After his failed attempts to capture the ruthless crook and serial murderer FantÃ´mas, Inspecteur Juve becomes the victim of a virulent press campaign which accuses him of being FantÃ´mas himself. Whilst Juve languishes in a prison cell, his friend, journalist Fandor, attempts to clear his name by tracking the real FantÃ´mas. Meanwhile, the police are investigating the disappearance of a debt collector. An American detective Tom Bob finds the body concealed in a newly built wall and offers to carry out his own investigation to find FantÃ´mas. Lady Beltham, former lover and victim of FantÃ´mas, receives a visit from Tom Bob, whom she instantly recognizes as FantÃ´mas. The arch-criminal compels her to organize a charity ball, ostensibly to raise funds to bring FantÃ´mas to justice. Hearing about the ball, and suspecting that FantÃ´mas will almost certainly be there, Fandor decides to attend, dressed as the infamous criminal.