Young journalist Tintin and his dog Snowy are browsing in an outdoor market in 1940s Brussels, Belgium. Tintin buys a miniature model of a ship, the Unicorn, but is accosted by an Interpol officer, Barnaby, and a ship collector, Ivan Ivanovitch Sakharine, who both unsuccessfully tried to buy the model from Tintin. Tintin takes the ship home, but it is accidentally broken in an incident between Snowy and a cat. A parchment scroll slips out and rolls under a piece of furniture. Meanwhile, bumbling police detectives Thomson and Thompson are on the trail of a pickpocket, Aristides Silk.