Greg and the Texas Rose crew make friends with Briggs, the captain of the long missing Mary Celeste. Briggs is the unofficial leader of the human slaves the Atlanteans' have captured, including his daughter, Delphine. Briggs informs them they will be given gills, thus will never be able to return to the oxygen-rich surface. They will then help protect Atlantis from the constant attacks of creatures known as Zaargs. A sudden Zaarg attack claims the life of Briggs, so Delphine helps Greg and the crew escape. Delphine shows the men a tunnel that will lead them into Atraxon's palace, where they can rescue Charles.
