 Learning that Müller's plane had crashed off the coast of Kiltoch, a Scottish coastal village, Tintin travels there to continue his investigation. At Kiltoch, an old man tells him the story of Black Island — an island off the coast where a "ferocious beast" kills any visitors. Tintin and Snowy travel to the island, where they find that the "beast" is a trained gorilla named Ranko. They further discover that the forgers are using the island as their base, and radio the police for help. Although the criminals attempt to capture Tintin, the police arrive and arrest the criminals, with Ranko going to a zoo.
