In 1967, Benjamin Braddock, aged 20, has earned his bachelor’s degree from a college on the East Coast and has returned home to a party celebrating his graduation at his parents’ house in Pasadena, California. Benjamin has no idea of what to do with his life and is visibly unhappy as his parents deliver accolades and neighborhood friends ask him about his future plans. He hides from those who try to congratulate him. Mrs. Robinson, the wife of his father’s law partner, insists that he drive her home. Benjamin is persuaded inside to have a drink and Mrs. Robinson attempts to seduce him. She invites him up to her daughter Elaine’s room to see Elaine’s portrait and then enters the room naked, making it clear that she is available to him. Benjamin rejects her but a few days later, he awkwardly organizes a meeting at the Taft Hotel, where he registers under the pseudonym Gladstone.
Benjamin spends the rest of the summer relaxing around the pool by day, refusing to select a graduate school, and seeing Mrs. Robinson at the hotel by night. He discovers that he and Mrs. Robinson have nothing to talk about. However, after Benjamin pesters her one evening, Mrs. Robinson reveals that she entered into a loveless marriage when she accidentally became pregnant with Elaine. Both Mr. Robinson and Benjamin’s parents encourage him to call Elaine, but, in private, Mrs. Robinson forbids him.
Benjamin decides to take Elaine on a date in order to ruin it: he ignores her, drives dangerously, and takes her to a strip club. After she runs out of the club in tears, he changes his mind, apologizes for his behavior, and discovers that Elaine is someone he is happy to be around. In search of a late-night drink they visit the Taft Hotel, but when the staff greet Benjamin as “Mr. Gladstone”, Elaine deduces that he has been having an affair with a married woman. She accepts his acknowledgement that the affair is over, but an angry Mrs. Robinson threatens to tell Elaine her version of their affair. To prevent this, Benjamin tells Elaine that the married woman was her mother.
Elaine is disgusted and returns to school at Berkeley. Benjamin follows her there and tries to charm her. She reveals that her mother’s story is that he raped her while she was drunk, and she refuses to believe that her mother actually seduced Benjamin.
After stalking her for several days and continuously proposing to her, Benjamin begins to make amends with Elaine. However, Mr. Robinson arrives at Berkeley after learning about the affair, confronts Benjamin at his rooming house, and threatens to put him behind bars if Benjamin sees his daughter again. Mr. Robinson then forces Elaine to drop out of college and takes her away to marry Carl, a classmate with whom she briefly had a relationship.
Returning to Pasadena in search of Elaine, Benjamin breaks into the Robinson home but encounters Mrs. Robinson. She tells him he will not be able to stop the wedding with Carl and then calls the police, claiming that her house is being burglarized.
Benjamin visits Carl’s fraternity brothers who tell him that the wedding is in Santa Barbara that morning. He rushes to the church and arrives just as Elaine is married, witnessing the kiss. He bangs on the glass at the back of the church and screams “Elaine!” frantically. After hesitating, Elaine screams “Ben!” and looks at him pitifully. He rushes toward her, and a fight ensues as guests try to stop the two from leaving together. Elaine manages to break free from her mother, who then slaps her. Benjamin manages to keep the guests at bay by picking up a large cross and wielding it, then jamming the church doors shut with it. Both he and Elaine then run into the street to flag down a passing bus and take the back seat, eloping.
However, as they settle into their seats, their faces change from happiness to uncertainty as “The Sound of Silence” plays.