The story revolves around a robot named Andrew, who by some irregularity in his positronic pathways is able to independently create wooden carvings. As creativity is not a part of a robot’s skills, his owner, Gerald Martin (Sir), sees him as extremely unique and allows Andrew to sell his carvings, keeping half.
As his family gets older, Andrew uses his money to keep himself in good shape, and expands his creativity and knowledge beyond what any ordinary robot would. Andrew asks Sir to allow him to buy his freedom, and on his deathbed, Sir relents, not accepting Andrew’s money. Andrew begins wearing clothes and going to the library to further his knowledge. He also, with the help of Sir’s grandson, a lawyer, begins to change the legal system as it pertains to robots, starting by banning orders to self-harm, meant to protect Andrew.
Soon, Andrew begins to drastically alter his own body, experimenting and designing parts himself, with the ultimate goal of being unrecognizable as a robot. He gives himself digestive and excretory systems, hoping that eventually he will be officially declared to be a man. However, on his 150th birthday, he is called the “Sesquicentennial Robot.” Their reservations seem to be because of his immortality.
His final modification changes their minds: He alters his positronic brain so that it will decay with time, arranging to live through his 200th birthday. He goes before the World Legislature, telling them what he has done from a wheelchair, and on his birthday they declare him the “Bicentennial Man.”
If this plot sounds familiar, that would be because it was made into a film in 1999 starring Robin Williams. The film follows the basic premises and names fairly closely, but in it’s details it is not particularly faithful to Asimov‘s original. The story, like “Nightfall” and “The Ugly Little Boy,” was expanded into a novel by Asimov and Robert Silverberg in 1993 called The Positronic Man.