The Mysterious Island
The film is loosely based on the back-story given for Captain Nemo in the novel "The Mysterious Island", and might more properly be thought of as a prequel to "Twenty Thousand Leagues Under the Sea". It is the story of Count Dakkar (Captain Nemo's real name is revealed to be Prince Dakkar in "The Mysterious Island"), how he built his submarine, how he was betrayed, and how he became an outcast seeking revenge.