The story revolves around young reporter Tintin , his dog Snowy , and his friend Captain Haddock , who discover a riddle left by Haddock's ancestor, the 17th century Sir Francis Haddock , which can lead them to the hidden treasure of the pirate Red Rackham.
To unravel the riddle, Tintin and Haddock must obtain three identical models of Sir Francis's ship, the Unicorn , but they discover that criminals are also after three model ships and are willing to kill in order to obtain them.
The Secret of the Unicorn was a commercial success and was published in book form by Casterman shortly after its conclusion. Two strangers, model ship collector Ivan Ivanovitch Sakharine and antique-scout Barnaby , independently try and fail to persuade Tintin to sell the model to them.
Tintin also meets detectives Thomson and Thompson on a secret mission looking out for a pickpocket ; however, both their wallets are repeatedly stolen throughout the story. At Tintin's flat, Snowy accidentally knocks the model over and breaks its mainmast. Having shown the ship to Haddock, Tintin discovers that the ship is named the Unicorn , after a ship commanded by Haddock's own ancestor.
While Tintin is out, the ship is stolen from his apartment; in the following investigation, he discovers that Sakharine owns an identical model, also named the Unicorn. At home, Tintin discovers a miniature scroll, and realises that it must have been hidden inside the mast of the model.
