While browsing on the Brussels Voddenmarket/Marché aux puces at the Vossenplein in the Marollen, Tintin purchases an antique model ship which he intends to give Captain Haddock.
Upon hearing of the riddle, Captain Haddock explains that the Unicorn was a 17th-century warship captained by his ancestor, Sir Francis Haddock, but seized by a pirate band led by Red Rackham.