After World War Three, new powers rise to dominate Earth. In the waters of the Caribbean, four strangers have banded together to face the armies of invading Neo-Nazis. Jed, Richard, and Toots are joined by the mysterious Melissa, a former captive of the facist troops. Fleeing aboard the submersible Sappho 3, the four are pursued by a fleet of Nationalist ships determined to kill or capture them all. Melissa has a daring plan to escape, but if it fails, Jed, Richard, Toots, and Melissa will suffer at the evil hands of the Neo-Nazis.