Hernández y Fernández
Following the culmination of his previous "Tintin" adventure, "Red Rackham's Treasure", Hergé had agreed to a proposal that would allow the newspaper to include a detective story revolving around his characters, Thomson and Thompson. Titled "Dupont et Dupond, détectives" ("Thomson and Thompson, Detectives"), Hergé provided the illustrations, and the story was authored by ' crime writer Paul Kinnet. While this was being serialised, Hergé began contemplating ideas for his new "Tintin" adventure, toying with the idea of a story surrounding a dangerous invention that Calculus had developed. The story was probably inspired by an article authored by ' science correspondent, Bernard Heuvelmans, and while Hergé did not use this idea at the time, he revived it a decade later as the basis for "The Calculus Affair".