During the late 18th century, smuggling has become standard practice for fishermen around the British coast. When a band of pirates, led by Black John (Bernard Lee), begin luring ships to their doom at Smuggler's Bay, the local community beg squire Trevenyan (Peter Cushing) to bring an end to the wanton pillaging and murder. The squire, however, has issues of his own, not least of all Black John, who has knowledge of Trevenyan's past that could be used against him should he attempt to bring the pirate to justice.