In Red Rackham's Treasure (1944), sequel to The Secret of the Unicorn (1943), Tintin and the Thom(p)sons accompany Captain Haddock on a journey in the footsteps of the Captain's illustrious ancestor, Sir Francis Haddock. The parchments discovered in the previous adventure are in fact a treasure map pointing the way to the hidden gold and jewels of a notorious pirate, Red Rackham. A new character, named Professor Cuthbert Calculus, will prove invaluable in the search for the lost treasure; by the end of the adventure Calculus will also help Captain Haddock to acquire his family's ancestral home, Marlinspike Hall. This story is full of twists, turns and surprises, not least the moment when Professor Calculus demonstrates a new type of machine for underwater exploration...