The Secret of The Unicorn (The Adventures of Tintin 11)
Hergé
The classic graphic novel. Tintin stumbles across a model ship at the Old Street Market. Only it isn't just any model ship-it's the Unicorn, carved by one of Haddock's ancestors, and it holds a clue to finding pirate treasure!
You can download it as an ebook, read it as a pdf if you want.