Fantômas has been arrested and is jailed in Brussels, but inspector Juve wants him arrested and sentenced for all his crimes in France. Thus Juve settles Fantômas' escape so he can be traced to his gang's, in Saint-Calais - France, where apaches Paulet and Ribonard have just robbed the diamonds of the broke Marquis de Tergall. On his way Fantômas kills justice Pradier and decides to go under this disguise when he finds that Pradier had just been appointed to Saint-Calais' court.