When Kurt Austin, the leader of an exploration team from NUMA (National Underwater & Marine Agency), rescues beautiful marine archaeologist Nina Kirov, he becomes the next target of Texas industrialist Don Halcon. A madman bent on carving a new nation out of the southwestern United States and Mexico, Halcon hatches a scheme which hinges on Nina's recent discovery involving Christopher Columbus and a priceless pre-Columbian artifact found on the sunken Andrea Doria.