A meaningless little spat is keeping Spirou and Fantasio apart that day, when the young bellboy sees his friend in the company of a mysterious neighbour. Shortly afterward, a jewellery shop is robbed, and the owner identifies Fantasio, who has come to cover the event for his newspaper, as his aggressor. When the very next day a priceless Egyptian mask is stolen live on TV by … Fantasio, Spirou is left with little choice but to investigate.