The Earth-Tube

The Earth-Tube (1929), a Yellow Peril sub-genre novel, in which Asians take advantage of their possession of the invulnerable metal undulal to tunnel under South America, which they soon conquer. After a young hero has penetrated the secret, catastrophic explosions close the tunnel, inundating South America but sparing the USA, which has transformed itself into a socialist regime in response to the free gold which the Asians have been raining from the skies in an effort to destabilize the great capitalist democracy.