A cynical young American, Thomas Doubting, stumbles upon a magical amulet which takes him on a mysterious journey to the island of Sinmouth. The eccentric locals believe he is the lost legend of "Mumbo Jumbo" - an entity who will restore their fortunes and rescue the beautiful Princess Vanilla. On his journey, the Mumbo Jumbo discovers Sinmouth's dark secret and saves the inhabitants from their greatest enemy and his villainous slave.