Tintin is informed by Thomson and Thompson of a case involving the ramblings of a drunken man, later killed, found with a scrap of paper from what appears to be a tin of crab meat with the word "Karaboudjan" scrawled on it. His subsequent investigation and the kidnapping of a Japanese man interested in giving him a letter leads Tintin to a ship called the Karaboudjan, where he is abducted by a syndicate of criminals who have hidden opium in the crab tins. Tintin escapes from his locked room after Snowy chews through his bonds and Tintin knocks out a man sent to bring him food, leaving the man bound and gagged in the room. Tintin encounters Captain Haddock, an alcoholic sea captain, who is manipulated by his first mate, Allan, and is unaware of his crew's criminal activities. Tintin hides in the locker under the bed and defeats Jumbo, the sailor left in the cabin, while Allan thinks Tintin has climbed out of the porthole back into the storeroom. He blows open the storeroom door, then finding it empty goes back to the Captain's room, where he finds Jumbo tied to a chair and gagged. Escaping the ship in a lifeboat after sending a radio message to the police about the cargo, a seaplane tries to attack them. Tintin and the Captain hijack the plane, tie up the pilots, and try to reach Spain. Haddock's drunken behaviour in a storm causes them to crash-land in the Sahara, where the crew escapes.[1]
After trekking across the desert and nearly dying of dehydration, Tintin and Haddock are rescued and taken to a French outpost, where they hear on the radio the storm sunk the Karaboudjan. They travel to a Moroccan port, and along the way are attacked by Tuareg tribesmen, defending themselves with French MAS-36 rifles. At the port, members of his old crew kidnap the Captain after he recognises their disguised Karaboudjan. Tintin meets Thomson and Thompson who got his message, and they learn that the wealthy merchant Omar ben Salaad sold the crab tins; Tintin tells Thomson and Thompson to discreetly investigate. Tintin tracks down the gang and saves the Captain, but they both become intoxicated by the fumes from wine barrels breached in a shootout with the villains. Haddock chases a gang-member from the cellar to an entrance behind a bookcase in Salaad's house. Upon sobering up, Tintin discovers a necklace of a crab with golden claws on the now-subdued owner of the wine cellar, Omar ben Salaad, and realizes that he is the leader of the drug cartel. Allan steals a boat and tries escaping, but Tintin captures him. The police arrest the gang and free the Japanese man, who introduces himself as Bunji Kuraki, a police detective who was trying to warn Tintin of the group he was up against. He had been investigating the sailor on Haddock's crew who drowned; the sailor was on the verge of bringing him opium before he was eliminated. Turning on the radio, Tintin learns that, thanks to him, the entire organisation of the Crab with the Golden Claws is behind bars