A 17th century Cornish town - villainous pirates roam the seas searching for treasure while the townspeople have turned to smuggling, wheeling and dealing in contraband. Into this wild and remote place the TARDIS materialises and the First Doctor and his companions find themselves caught up in the dubious activities of the locals. When the Doctor is unwittingly given a clue to the whereabouts of the treasure the pirates are determined to extract the information - whatever the cost.