In the second episode of the trilogy Fantômas kidnaps distinguished scientist professor Marchand with the aim to develop a super weapon that will enable him to menace the world. Fantômas is also planning to abduct a second scientist, professor Lefebvre. Journalist Fandor develops an ingenious scheme whereby he disguises himself as Lefebvre and attends a scientific conference in Rome, Italy to lure Fantômas into attempting to kidnap him.