The movie starts over half a century ago in 1955. Tintin is a 17-year-old journalist. His dog Snowy are doing shopping in an outdoor store. It’s located in the city of Brussels, Belgium. That’s where Tintin purchase a mini model of a ship named the Unicorn. However, an international police officer named Barnaby and a ship collector named Ivan Ivanovitch Sakharine then both try to purchase the model of a ship from Tintin.
Tintin then takes the model to his home. In an accident that involves Snowy and a cat, the ship brakes. It results in the paper scroll falling out of the ship model and then rolling underneath the apartment furniture. Tintin doesn’t notice what happens.
During this time two police detectives are following a pickpocket named Aristides Silk. After Tintin visits Maritime Library in order to find clues he returns and discovers that the Unicorn model is missing because someone has stolen it.
He then goes to visit Sakharine and makes the accusation he stole the model. However, when he sees the Unicorn model he observes that it’s not broken. That shows that there are actually two models instead of just one. When he gets back home Snowy then shows his owner the scroll.
They read the message but then Barnaby arrives. He’s killed while trying to get the Unicorn one last time. Tintinthen places the scroll inside his wallet. However, Silk is able to steal it during the next day.
Later Tintin gets abducted by Sakharine’s employees. HE’s then imprisoned. Tintin learns that he had teamed up with astaff of the ship and was the leader of a mutiny in order to take control of the ship. Tintin is able to meet the character Captain Haddock who is always drunk and isn’t aware what’s happening on his own ship. Tintin, Snowy, and Haddock are able to outrun the crew members and are able to escape in a lifeboat.
They later seize a plane and fly towards a port. However, the seaplane ends up crashing in a desert area because it has low fuel. While they’re walking in the desert Haddock remembers some facts about one of his ancestors. It was a 1600s captain of the ship named Unicorn. A group had attacked the treasure ship. The story implies that there was actually a total of three Unicorndifferent models. Each of the models contained a scroll. They can show the coordinates of the Unicorn ship that had sunk as well as its treasure.
In the end, Sakharine and Haddock have a sword duel. Haddock wins the fight. Tintin and Haddock then use the three scrolls to find part of the treasure and a clue about the Unicorn.