Opis: One night, a pair of criminals discreetly break into an aquarium in Brussels and steal a large and priceless pearl. When the security guards on duty see that the shell where the pearl had previously been was empty, they run away to raise the alarm. In the guards' absence, the criminals discreetly place a fake pearl of similar dimensions to the original into the shell before leaving. When the guards return with the museum's director and see the pearl back in the shell, the director initially thinks that the guards were making up the story of its theft, but later he has second thoughts after recalling that a similar thing had happened in another museum two weeks earlier.In the meantime, Tintin, his dog Snowy and Captain Haddock arrive in the Balkan nation of Syldavia in order to join their friend Professor Cuthbert Calculus, who has rented a villa on the edge of Lake Pollishoff, also known as the Lake of Sharks, in order to build his latest invention. They meet police detectives Thomson and Thompson at Syldavia Airport and discover that the twins are also heading for the villa that Calculus has rented for a special mission.The four men and dog fly toward Calculus' villa in a hired plane, but during the flight the plane gets into some engine trouble, and the pilot bails out with the only parachute on board. Tintin tries to land the plane safely, but it ends up on fire on the edge of a cliff. All of the passengers are saved when two local children, Niko and his sister Nushka, throw a rope onto the plane's tail and get their dog Gustav to pull it back from the cliff. As the passengers introduce themselves to the children, they are watched by their pilot, who had deliberately staged the engine's problems, who contacts someone called "Neptune", using a walkie-talkie concealed in his binoculars, to inform him that Operation Sardine was not successful.Niko and Nushka give their new friends a lift in their wagon, but when they learn where the others are going, they warn them that there is a curse on the lake, which has an old, submerged town at its bottom. They all arrive at the lakeside villa where Calculus demonstrates his invention, which is a camera that is capable of projecting holographic images. His ultimate aim is to build a machine that can make actual copies of physical objects.That night over dinner, Thomson and Thompson explain their mission - they are at the villa to act as bodyguards for Calculus because they suspect that a criminal organization that specializes in making forgeries of artworks wants to steal the duplication machine after Calculus builds it. That night, after everyone has gone to bed, Snowy hears a noise outside and wakes Tintin up, but Tintin dismisses the noise as bird calls. The noise actually comes from a well near the villa where Calculus' housekeeper, Madame Flik, is drawing up a bucket, but instead of water, the bucket contains a walkie-talkie. Madame Flik leads a double life as "Agent Rameses" and uses the walkie-talkie to make contact with "King Shark".Next morning, Niko and Nushka lead Tintin on an exploration of the country, unaware that there are surveillance cameras spying on their every move, and Thomson and Thompson play golf with Haddock as Snowy meets a frogman who has received some plans that Madame Flik stole from Calculus' laboratory. The frogman escapes by jumping in the lake, but not before Snowy bites a piece off one of his flippers, witnessed by the detectives and Haddock. After they let Tintin know about what has happened, he allows both Snowy and Gustav to sniff the flipper. Haddock follows Gustav to a pile of abandoned tyres, but Snowy leads Tintin to a buried chain. Tintin pulls the chain and discovers a concealed passage that leads to a cave that the criminals have used to stash the works of art that they have stolen. After Tintin gets sealed inside the cave, which Snowy remains outside of, he discovers an underwater tunnel that leads from the cave to the lake. He dives into the tunnel, but on the way out he gets trapped by a wire net. Snowy sees the bubbles, dives into the tunnel and chews through the net, allowing Tintin to avoid drowning and make it back to the surface of the lake.Back at the villa, Calculus demonstrates his latest invention to Niko and Nushka. He has been able to use a piece of a special soap to make a copy of any object. The effect is only temporary, however, as the copy soon turns back into a piece of soap. The criminals use laughing gas to attack the villa and kidnap Niko and Nushka. They are pursued by Tintin and Haddock, but the criminals get away. They leave behind a tape player that contains a message from "King Shark", their leader, that says that the children will be returned in exchange for Calculus' invention, but Tintin must do the exchange by himself and must not call the police. Tintin thinks that there is something familiar about the voice of King Shark.Tintin, Haddock, Calculus and the detectives then comb the villa in a search for bugs, and during the search, Tintin discovers a secret passage that leads to the bottom of the well, finding the bucket with the walkie-talkie in it there. A criminal monitoring the radio notes that it is almost time for Rameses to report. Madame Flik heads to the well with the intention of warning King Shark that the visitors are getting too inquisitive, but she is caught by Tintin, who orders her back to the villa. Tintin decides to go to the police, against the message's advice, and concocts a ruse in order to cover his tracks. As he and Snowy make their way towards the town, they happen to meet an old friend of theirs, opera singer Bianca Castafiore, who gives them a lift into the town and even directs Tintin on where to find the police station. Although the police chief listens to Tintin's story, his hands are tied because the border between Syldavia and their rival nation Borduria runs through the middle of the lake and the chief does not want to risk a diplomatic incident.Two days later, Tintin finally returns to the villa with the submarine that Calculus had built to search for Red Rackham's treasure. Tintin plans to meet the criminals on the beach, and have Haddock follow him in Calculus' submarine when the crooks take him and Calculus' machine to their leader. Tintin arrives at the arranged meeting point, where the criminals pick him and the machine up and use their submarine to take them to the lake's submerged city, which they have been using as their base. They lead him to their mastermind, King Shark, which Tintin finds out is his old nemesis Rastapopoulos, who reiterates the promise from the message to release the children in exchange for the machine. However, Niko and Nushka, unaware of Tintin's arrival, have escaped from the cell that they have been in, hijacked an underwater tank and used it to break through a sheet of glass that was supposedly unbreakable and escape.Rastapopoulos uses a computer to regain control of the tank, but when he sees the submarine that Haddock is in on his monitor screen, he uses the tank's controls to fire torpedoes at the submarine. Tintin tries to stop him and gets into a fight with the crooks in the process. Eventually, one of the torpedoes hits the submarine, jamming its propulsion systems. Rastapopoulos then uses the tank's controls to return it to the base. While they wait for Niko and Nushka to arrive, Rastapopoulos takes Tintin to his office and shows off his art collection, boasting that with Calculus' machine, they can make several copies of each masterpiece and sell all of them off for a large sum of money.Rastapopoulos then tries out Calculus' machine on a box of cigars. At first, the reproduction looks perfect, but it proves to be highly unstable and grows to an enormous size, and almost crushes both Rastapopoulos and his lieutenant before breaking through the office door in the sight of the criminals bringing Niko and Nushka back from the recaptured tank. Rastapopoulos accuses Tintin of sabotage and gets even by locking Tintin in the same chamber as Niko and Nushka. Soon after, he finds out that there are police boats patrolling the lake's waters, so he decides to evacuate the underwater base and orders the criminals to take the art from his office and the rest of the underwater city to the cave. He then starts flooding the chamber in which Tintin, Niko and Nushka are with water and tells them that in one hour, the rising water will cause a float to press the switch of a device high on the wall, at which point the underwater city will self-destruct.Eventually, Haddock is able to regain some control of Calculus' submarine and bring it to the surface, where he finds a patrol boat with Thomson, Thompson and the Syldavian police chief. Down in the underwater city, with all of the other criminals safely evacuated from their base, Rastapopoulos and his lieutenant board their submarine and use it to leave the base for the final time. Tintin uses Nushka's hairpin to pick the lock of the chamber, allowing them and Niko to escape. They find some life jackets and an airlock. Tintin gets ready to open the airlock's outside gate at the very moment that the base explodes. The patrol boat with Haddock, the detectives and the Syldavian police chief spots Tintin, Niko and Nushka after they reach the lake's surface. The Syldavian police have captured the other criminals, but the mastermind and his lieutenant have already set their submarine on a course for Bordurian waters. Tintin and Haddock eventually commandeer a motorboat to go off in pursuit of Rastapopoulos, reasoning that as they are not Syldavian citizens, they are not bound by the same international conventions that would limit what the local police could do.Meanwhile, Rastapopoulos tries to bypass the border posts by navigating his submarine through a tunnel surrounded by a rocky reef, but realizes too late that he has forgotten to lower the periscope. It strikes one of the reefs and causes the submarine's hull to fracture on the reef on the other side of the tunnel. Forced to take the submarine up to the surface, as soon as the lieutenant tries to leave, he sees what he thinks is the ghost of Tintin. Rastapopoulos has a more rational explanation - Tintin escaped the explosion. The mastermind knocks the gun out of Tintin's hand, but it is caught by Haddock. Tintin, Snowy and Haddock bring Rastapopoulos and his lieutenant back to the patrol boat, where the friends are welcomed by the detectives, Niko, Nushka, Gustav and Calculus, while the Syldavian police arrest Rastapopoulos and the lieutenant and take them to the prison in Klow.When Tintin, Snowy and Haddock return to Calculus' villa, they find several locals who have arrived there in order to celebrate the end of the criminal gang's reign of terror. Some of them offer to teach Tintin how to dance the Blushtika, the national dance of Syldavia. When one of them is revealed to be Bianca Castafiore, Haddock is quick to retreat from the party and finds a place to try and have a quiet moment to drink some whisky, only for the bottle to get shattered by a golf ball hit by the detectives while they are playing golf. Haddock is annoyed by this at first, but he laughs over it along with everyone else.