Professor Calculus's friend develops a blue-skinned orange that can grow on any kind of land and survive harsh weather (in the manner of Lue Gim Gong) and therefore solve world hunger. The Professor and his friends, however, run afoul of gangsters who also covet the fruit. The adventure takes them from their home in Marlinspike Hall (Moulinsart), a fictional mansion that is presumably in Belgium, to Spain, where Calculus and another scientist are kidnapped.
Jean-Pierre Talbot
Tintin
Jean Bouise
Capitaine Haddock
Félix Fernández
Professeur Tournesol
Jenny Orléans
Bianca Castafiore
Ángel Álvarez
Professeur Zalamea
Franky François
Dupond
André Marié
Dupont
Pedro Mari Sánchez
Pablito
Max Elloy
Nestor
