William Markham, a merchant captain, is wrongly accused of piracy by Richard Barrons, who hopes to claim the captain's fortune after his death. Hanged for treason, Markham returns to haunt the man who betrayed him, bent on vengeance - and justice. But his spectre is only visible to Lady Arianna Halverson, a gifted psychic sensitive to those who have passed beyond this mortal realm. Now the evil Barrons plots to murder her brother as well - and force Lady Arianna to marry him. Healed by the magic of her amulet, Captain Markham assumes physical form to battle his nemesis and rescue Lady Arianna. But he cannot stay forever in the land of the living - unless her love can save him...