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'Machines', powerful computers that control the world's economy and production, start giving instructions that appear to go against their function. Although each glitch is only small, the fact that they exist at all is alarming. Dr Susan Calvin and Stephen Byerley, now World Co-ordinator, investigate.

It is 2052, and machines are in control of the world... luckily Asimov knows his audience will appreciate a good story, and doesn't resort to alarmism. Anyway, here the Machines' First Law is similar to the later Zeroth Law, that 'No robot may harm humanity', and it is this that causes the problems. Dr Calvin concludes that the "glitches" are deliberate acts by the Machines, allowing a small amount of harm to come to selected individuals in order to prevent a large amount of harm coming to humanity as a whole.