The Red Sea Sharks is the nineteenth of The Adventures of Tintin, a series of classic comic-strip albums written and illustrated by Hergé, featuring young reporter Tintin as a hero. Its original French title is Coke en stock ("coke in stock") referring to a slang term for African slaves.
The Red Sea Sharks is notable for bringing together a large number of characters from previous Tintin adventures, going all the way back to Cigars of the Pharaoh:
After watching a movie, Tintin and Captain Haddock round a corner and bump into General Alcazar, who drops his wallet. Tintin attempts to return it, but the hotel he claimed to be staying at has never heard of him, and when Tintin calls a phone number found in his wallet, the man refuses to talk to him. When Tintin and Haddock return home, they discover that the Emir's bratty, impossibly spoiled son Abdullah has been sent there for protection, along with a colourful entourage of servants and dignitaries who have established a bedouin-bivouac in the great hall of Marlinspike Hall.
Thomson and Thompson inform Tintin that they know of his meeting with Alcazar due to their investigation of an arms dealer called Dawson. They then tell him the name of the real hotel where the General is staying. At the hotel, Tintin and Haddock see Alcazar talking with Dawson, whom Tintin recognises as an enemy he met in The Blue Lotus.
Haddock returns the wallet to Alcazar, while Tintin follows Dawson and overhears him discussing how successful his sale of De Havilland Mosquitoes were in starting a coup d'état in Khemed. Tintin decides to go to Khemed and rescue the emir, who has been overthrown by Sheikh Bab El Ehr. Reluctantly, as usual, the Captain agrees to go along, partly because he knows it's his only chance of getting rid of Abdullah, whose practical jokes are getting too much for him.
Meanwhile, Dawson, realising that Tintin is again meddling in his affairs, resolves to take desperate measures.
At Wadesdah Airport in Khemed, Tintin and Haddock are turned back by customs, while someone (presumably an agent of Dawson) plants a bomb on the plane to "take care of them". The bombing is foiled by an engine fire, which forces the plane to crash-land minutes before the bomb goes off. Realizing that they best take a lower profile, Tintin and Haddock walk away from the crash site and slip in unobserved at night into Wadesdah. There they meet another old friend, the talkative Portuguese merchant Oliveira da Figueira. He helps them escape the city by dressing up as veil-wearing women. Once outside they meet a guide with horses and ride to the Emir's hideout (modelled on the ancient Jordanian city of Petra).
Their escape is reported however, and a leading figure in the new regime sends out a squad of armoured cars and Mosquitos to intercept them. The officer is Mull Pasha who is in fact Doctor Müller, an adversary whom Tintin fought against in The Black Island and Land of Black Gold. Thanks to a military miscommunication, the Mosquitos attack their own armoured cars instead of Tintin and his friends.
The Emir tells them about the ongoing slave trade run by the Marquis di Gorgonzola, an international businessman with whom the Emir had a falling out several months ago. The Marquis uses the pilgrimage to Mecca to capture and enslave African Muslim travellers. Tintin and Haddock leave for the Red Sea coast and board a boat for Mecca to investigate. They are attacked by the Mosquitos again; Tintin manages to down one with a German StG-44, but their schooner receives critical damage and they end up shipwrecked aboard a raft, along with Piotr Skut, the pilot of the downed plane. They are then picked up by di Gorgonzola's yacht, the Scheherazade, which happens to pass by, but di Gorgonzola isolates them from his guests and offloads them the next night to the SS Ramona, a tramp steamer. Unbeknownst to Tintin and Haddock, the Ramona is one of di Gorgonzola's own ships, used in the slave trade.
That night they are locked into their cabin by Allan, Haddock's former first mate, who commands the Ramona. A fire breaks out on the Ramona and the crew abandons ship. Tintin and Haddock force their cabin door open and manage to put out the fire, not realizing that the front of the ship was loaded with munitions. They then free a number of black African men (who speak Yoruba) from a rear hold and discover that they had paid for the voyage to Mecca, but were intended to be sold as slaves instead. Haddock attempts to explain the situation to them. Initially, many of them don't understand, or refuse to, thinking Haddock is lying. After some discussion, the men come around; an older member group recalls how some men from his village never returned from the Hajj. The Africans agree to help Haddock sail the ship to neutral territory in Djibouti, while Tintin and Skut attempt to fix the radio, which had been smashed.
Tintin finds a slip of paper in the radio room with an order to deliver "coke", and is puzzled. In shipping, "coke" would normally refer to a coal-derived fuel, but none is being carried (this is prior to the use of "coke" to mean "cocaine"). They are then approached by a dhow and take aboard an Arab who wishes to inspect the coke, puzzling Haddock, who claims they have none. The man then turns about and starts examining the physical strength of one of the Africans. With the nature of the term coke, a codename for slaves, clear to him, Haddock furiously confronts the Arab. The inspected black African manages to thwart the Arab's attempt to stab the Captain, and the slaver is thrown off the ship.
Di Gorgonzola (who is actually Rastapopoulos, the leader of the international drug smugglers from Cigars of the Pharaoh and The Blue Lotus) finds out from the Arab that Haddock has taken control of the ship, and sends a submarine to attack them. Tintin spots the submarine by accident just prior to attack. Haddock manages to outmaneuver a number of torpedoes, but all appears lost when the engines of the ship get stuck in half reverse. At this point the Ramona is saved by the arrival of aircraft from a nearby US cruiser, the USS Los Angeles, whose crew had been radioed by Tintin. The submarine makes one more attempt to destroy the Ramona by attaching a limpet mine to the front of the boat beside the explosives, but this is foiled when the diver is hit by the Ramona's anchor. A shark swallows the mine and swims away.
When the Los Angeles attempts to arrest di Gorgonzola afterwards, he fakes his own death by allowing a motorboat which he steers from his yacht to the cruiser to sink while he escapes in an inbuilt mini-submarine. Thinking him dead, Tintin, Haddock and Skut return to Europe to international acclaim for their efforts in exposing the slave traders. Soon afterwards, the Emir recaptures control of Khemed.