Nobody's Fool is a dramatic comedy film starring Paul Newman. Newman plays Sully Sullivan, an elderly man living in upstate New York. Sully is eccentric and all the other people in the town find him weird. He and his friend Rub spend their days picking up odd jobs in construction. He also has an ongoing feud with Carl, an area businessman. One of Sully's favorite ways to irritate Carl is to flirt with his wife. Sully is also trying to win a workman's compensation suit. He is claiming that his knee is bad and he cannot work. Of course, this is not the case and Sully is merely faking it.
Sully rents a room in a house from an elderly woman named Miss Beryl. Miss Beryl's son is a successful banker and he thinks Sully is a freeloader. He does his best to persuade his mother to kick him out. Miss Beryl's son wants to sell his mother's house to land developers. One day, Sully's son Peter comes for a visit. Peter and Sully have not spoken for years. The two men begin to work on repairing their relationship, which takes time. Sully does not want to give up his ways and in one scene, he even tries to steal Peter's snowblower. Sully also tries to connect with his grandson. Rub is a little jealous that Sully is spending all this time with his family but Sully learns to appreciate Rub as well.
Sully also has a temper problem and he ends up assaulting a police officer. However, because Sully has begun to work on his relationship with his family, they decide they want to support him. Carl's wife has also begun to see a change in Sully and she tells him that she is willing to leave Carl for him.