The Black Island
Bob de Moor, Hergé's assistant, was asked to change the synopsis and make it the sixth "Jo, Zette and Jocko" adventure. After a few sketches were made this project fell through as well, as Hergé asked Bob de Moor to modernize "The Black Island" instead. Hergé then turned his attention to "The Castafiore Emerald", which saw book publication in 1963.