Galactor wants to conquer the seven seas before it conquers the planet. to do this they use the old "ghost ship" routine in the Graveyard of Ships.
there have been five ships lost in the Graveyard, and they want to know why. the ISO has an underwater farm now, and the oceans are clean and pure. how far into the future is this series set? Galactor wants to destroy it as a demoralizing agent.
Dr. Nambu has been consulted, and has secretly sent his team to the island. everyone but Ryu is enjoying themselves, some more than others.
eventually the base is attacked, and the teams flies out to find the sub. which leads them into a trap. Condor Joe is kind of an idiot, so bound up in using the Bird Missiles that he wastes most of them on empty ships. then the saucers come out.
the saucers attach the Phoenix immediately, and there's several hundred of them. things look bleak for our heroes!
fortunately, Red Impulse and his men appear and wipe out the saucers in minutes. they leave, and Red Impulse identifies himself and tells Gatchaman they should meet later. this leaves Ken wondering if he's friend or foe...