Mary Yellan has her life changed after shipwreckers murder her father. When her mother dies of a broken heart not long afterward, Mary is forced to go and live with her Aunt Patience at her inn on Bodmin Moor. It's there that she discovers her slightly crazy Uncle Joss is the ringleader of the wreckers and that Jamaica Inn is their headquarters. Mary is determined to bring Joss and his gang to justice and calls upon Joss's brother Jem to help do so. But the respected squire of the nearby Cornish village is, in reality, the leader of the gang of murderous pirates who attack passing ships, kill their crews and steal their cargo.