The plot revolves around an evil Chinese general who has built a laser tunneling machine and proceeds to tunnel all the way under the Pacific, intent upon invading the USA. The intention was to place nuclear bombs under US cities and military bases. The subsequent catastrophe could be passed off as 'earthquake damage'. Seismologists in America detect the burrowing yellow peril and the US military investigates. Using an existing mine to breach into one of the Evil Chinese Tunnels (tm), Da Marines proceed to do a reccy and discover the nefarious goings-on. The army rush to develop their own laser tunneling machine to counter-attack Da Dirty Commies. Much running around by GIs through papier mache tunnels ensues. The US laser-mole blows up at a critical moment, however due to grit, determination, know-how and all-round GI can-do, the filthy godless commies are vanquished.