The fantastic Captain Nemo (here played by Herbert Lom) once again inspires the spirit of adventure in another Jules Verne classic. Captain Cyrus Harding (Michael Craig) leads three Union soldiers in a daring escape from a Confederate prison camp in a seized Confederate balloon. A raging storm forces the balloon over the ocean toward a Pacific island on which the group becomes marooned. The shipwrecked women share in the dangerous encounters the castaways have with a host of gigantic beasts (courtesy of Ray Harryhausen's special effects). Their fight for survival is aided by the mysterious Nemo of the submarine Nautilus, who, in an attempt to increase the world's food supply, helped create the strange animals. When a volcano erupts and threatens to destroy everyone, can Nemo save them?