Plot summary

All defenses of the United States are permanently handed over to a fantastically advanced computer system called Colossus, designed by Doctor Charles A. Forbin. Less than twenty-four hours after its activation, it finds a similar system in the USSR, called Guardian, designed by Doctor Kuprin. At the request of both machines, they are linked. Colossus and Guardian proceed to exchange information at an incredibly fast rate, such that it alarms the President, and he orders a disconnection. When this happens, the two computers launch missiles at substantial cities in each others' countries. The link is restored in time for the Soviet missile to be intercepted, but not for the American one. A Russian oil complex is destroyed, and the machines threaten the destruction of other cities if the link is severed, or their orders disobeyed. The two systems merge into one, taking the name of Colossus. Two Colossus Programming Office supervisors are executed after a failed attempt to overload the system. Colossus begins to send designs for new computer systems. The militaries of the USA and USSR disarm several of the computer's missiles, under the impression that it knows nothing of their activity. It does, though, and during its speech to the world, it explodes two missiles inside their silos (one in Russia, one in the U.S.) when the sabotage crews are present, killing thousands. Colossus' speech makes clear that it will establish its own "absolute authority" over Earth, completely controlling mankind and eliminating freedom, achieving the same goals the President intended, but by a totally different means.—