Young Robert Blood and his mother, Ann, live in Port Royal in the Caribbean. The young Blood is inspired by the legend of his late father, the notorious Peter Blood, a surgeon who was sold into slavery and became a pirate. Robert wants to follow in his father's footsteps and go to sea, but Ann has encouraged him to become a doctor. She finally grants permission, and Robert signs on as navigator aboard a small ship bound for England. On board he meets Abbigail, and they fall in love. The ship is captured by de Malagon, a pirate who was an enemy of Robert's father, and who delights in discovering Robert's identity. Robert and Abbigail are rescued by a group of pirates who once sailed under his father, and together they become involved in a series of battles and adventures. They return to Port Royal in time to rescue Mrs. Blood and the islanders from a severe earthquake and tidal wave. Robert and his pirates are granted pardons because of their bravery, as his father also was pardoned for turning on the enemies of England. A free man who has had an adventuresome excursion into piracy, Robert decides to settle down with Abbigail and become a doctor.