Attorney Stephen Byerley announces his candidacy for mayor of an American city. His chief opponent, Francis Quinn, visits US Robots with a strange request: He asks them to prove that Byerley is not human but a robot who therefore cannot run for office. Like a robot, Byerley is never seen to eat, drink, or sleep. No robots are permitted on inhabited planets; if word got out, US Robots would be in big trouble.

Dr. Lanning and Dr. Calvin contact Byerley, who guffaws at the idea that he is a robot. Lanning says all he must do is eat a meal in public. Dr. Calvin offers Byerley an apple; he bites into it. Dr. Calvin says this proves nothing, as a humanoid robot would be able to perform such actions.

Byerley drives home, where he meets his housemate, John, who’s wheelchair bound. Byerley describes his encounter with the US Robots executives and Quinn’s campaign to prove him a robot. He and John discuss strategy.

That evening, Lanning and Dr. Calvin meet again with Quinn, and they point out that, to prove Byerley is a robot, Quinn would have to dismantle him. The only other proof would be if Byerley broke one of the Three Laws of Robotics; obeying those laws, on the other hand, proves nothing, as humans can do the same.