The Black Island is the seventh of The Adventures of Tintin, written and illustrated by Hergé, featuring young reporter Tintin as the hero.While walking in the Belgian countryside Tintin sees an airplane making an emergency landing. He goes to help and notices that it does not have a registration number on it. As he approaches the plane he is shot by the pilot. Tintin recovers at a hospital where police detectives Thomson and Thompson inform him that a similar plane has crashed in a field in Sussex, England. Tintin decides to investigate for himself.
Tintin takes a train from Brussels to the coast in order to board the ferry from Osted to Dover, England. . During the journey he is framed for the assault and robbery of a fellow passenger (who is in fact part of the mysterious criminal gang Tintin has inadvertently stumbled upon). Thompson and Thomson arrest Tintin, but he escapes by handcuffing them to each other while they are asleep.
Arriving in England, Tintin is kidnapped by the same men who framed him. They take him to a clifftop, intending to make him jump off it, but Tintin escapes with Snowy's help. His investigations lead him to Dr. J.W. Müller who, with his chauffeur Ivan, is part of a gang of money counterfeiters, led by Puschov, the so-called victim on the train.
Tintin's pursuit of Müller and Ivan results in a plane crash in rural Scotland, where a friendly farmer gives him a kilt to wear. He visits the pub in the coastal village of Kiltoch, where he is told strange stories about the Black Island, where an evil beast is said to roam, killing humans. Tintin buys a boat from a villager and heads for the island, where he is almost killed by a gorilla named Ranko and finds his boat missing. Stranded on the island, Tintin discovers that it is the hideout of the gang of counterfeiters led by Puschov and Müller.
Tintin temporarily manages to subdue the gang (they free themselves shortly afterwards) and calls the police on their radio signaling device after watching Thompson and Thomson win an air show race on a television set (though they didn't mean to). After a desperate holding-out action (in which Ranko's arm is broken), the gang is captured and Tintin returns to mainland Kiltoch, but the media and press do not stay very long after Ranko appears. The gang is jailed, the now submissive Ranko is placed in a Glasgow Zoo, and Tintin decides to return home via a plane trip, which Thompson and Thomson, who have reconciled with Tintin, turn down due to their previous harrowing experience.