Eighteen years later, Mrs. Hardin reveals to Annette the secret of the map, just as Hernandez and Ponto, two evil soldiers of fortune who had earlier worked for her father, come in search of it. Meanwhile, Joe and Neal apply for admission to Annapolis, but because Joe has slipped stolen papers into his adopted brother’s pocket, Neal is accused of cheating and dismissed from the Academy. Instead he enlists as a common sailor in the Navy. During training, he is visited in Newport by his mother and Annette, who is attacked by the villains in search of the map in her possession. Realizing that its secret inscription reveals the coordinates of the Lost Isle, Annette, Neal, and their party set off to find the site and its treasure. In close pursuit are Hernandez and Ponto, as well as the young adventuress Inez Castro and a gigantic man-beast named the “Brute.”
 
 
Over the next few episodes, Neal repeatedly comes to Annette’s rescue: in the smugglers’ “Cavern of Death”; at the hands of gunrunners and attacking revolutionists; from the “Sun Worshippers” who are prepared to sacrifice her; from a “Yellow Fever” outbreak on a mosquito-ridden island; in a jaguar pit (into which Ponto falls and is killed); and on the “rolling terror” of a runaway train whose brakes have been cut.
 
 
After granting the U.S. Government the right to establish a coaling station on the lost island to which she has been able to establish a claim, Annette gets shipwrecked among cannibals and is pursued by a crew of pirates. Once again, she and her party are rescued by Neal. Meanwhile, the “Brute,” whom the cannibals believe to be a god risen from the sea (and who had earlier delivered Annette from harm), regains his senses and proves to be her long-lost father. He follows Hernandez to the edge of a cliff, where the villain falls to his death. With their greatest enemy now removed, the Illingtons and the Hardins are finally able to enjoy the fortune derived from the island’s mines, while Inez, as reparation for her part in the conspiracy, enters a convent. As The Moving Picture World reported, “This wonderful serial closes with Annette and Neal having come to a perfect understanding as to how they intend to spend the remaining years of their lives.”
 
 
The serial (whose scenario, based on a story by William Hamilton Osborne, was written by Douglas Bronston) was completed in record time, with Balboa offering director William M. Harvey a $500 bonus if he met the twelve-week deadline. Harvey did, but as some film scholars noted, the rush was evident in the quality of the production, which was a box-office disappointment. Nonetheless, Neal of the Navy remains notable for its title character and for the credible performances of William Courtleigh and Lillian Lorraine.