

The four men and dog fly by hired plane to Calculus' house, but during the flight they get into some engine trouble and the pilot bails out with the only parachute. At the airport they run into Thompson and Thomson, who are also heading for Calculus on a special mission. They have come to join their friend Professor Calculus who has rented a villa near a lake in order to build his latest invention. Meanwhile, Tintin, Snowy and Captain Haddock arrive in Syldavia, a country in the Balkans. When the guards return with the director and the director sees the fake pearl, he thinks the guards were making it up, but then has second thoughts about the incident as a similar case happened at another museum two weeks before. The criminals take advantage of the guards' absence by putting a fake pearl, the same size as the real one, in the shell. As soon as the security guards on duty see the empty shell, they rush away to raise the alarm. One night, in Brussels, Belgium, a pair of criminals discreetly break into the aquarium and steal a priceless pearl. It was later adapted into a comic book with still images from the film used as illustrations.

It was not written by Hergé (who merely supervised), but by the Belgian comics creator Greg (Michel Regnier), a friend of Hergé. Tintin and the Lake of Sharks (French: Tintin et le lac aux requins) is a 1972 French-Belgian animated adventure film based on The Adventures of Tintin, directed by Raymond Leblanc.
