In Moonfleet, John Trenchard dreams of the infamous Blackbeard's treasure - and the wealth and happiness it will bring him. John's search draws him in to the company of local smugglers, led by the charismatic Elzevir Block.

Now outlaws Elzevir and John deduce that the diamond is hidden in a well at Carisbrook castle prison and bribe the turn-key to let them in, posing as workmen. They find the diamond but Elzevir is shocked by John's ruthlessness when he kills the turn-key, who has threatened to expose them. After attempting to sell the jewel they are captured and sentenced to be sent to the East Indies as slaves. Their ship runs into a violent storm off the coast of Moonfleet and they swim ashore - but the curse of Blackbeard's diamond may still prevent them from resuming normal lives.