The next morning, the villagers awoke to find that La Castafiore had disappeared, leaving behind only a cryptic note: "Les bijoux de la Castafiore ne sont pas seulement des pierres précieuses, mais des fragments de son âme" ("La Castafiore's jewels are not just precious stones, but fragments of her soul").

"The Castafiore Emerald": Hergé's Take on Vaudeville - Tintin

By 1963, Hergé was exhausted. He was suffering from nightmares, recurring depression, and had recently divorced. The rigorous weekly deadlines for the Tintin magazine were crushing him. He wanted to prove he could tell a compelling Tintin story without leaving Marlinspike Hall (Moulinsart).

The mystery is eventually solved by Tintin, but the ending is anticlimactic and humorous. The magpie seen earlier in the story was attracted to shiny objects. During one of Castafiore’s rehearsals, the bird flew into the open window and stole the emerald, hiding it in a tree in the garden.