In "12 Angry Men," a 12-man jury in New York deliberates the guilt of a defendant in a homicide trial. A lone dissenting juror must convince the rest of his peers of the defendant's innocence, despite their near-unanimous agreement otherwise.
The film begins at the trial of a teenage boy, accused of stabbing and murdering his father. The 12-man jury is sent to deliberate on the boy's guilt. Initially, the there is a near-unanimous consensus that the boy is guilty, but one juror dissents on the grounds of reasonable doubt, much to the chagrin of his peers. The following 90 minutes involves the dissenting juror's attempts to re-analyze evidence to prove that the testimonies against the boy are largely hearsay and circumstantial.
The dissenting juror calls into question and disproves the testimony of key witnesses, including the old man living downstairs and the lady across the street. He cites "emotional distress" as to why the boy could not name the movie he saw when providing his alibi and questions the use of the murder weapon (a switchblade), which was used in a way contrary to the boy's knowledge. In the course of the deliberations, the juror convinces his peers to change their verdicts one-by-one, exposing their prejudices and bigotries, which range from distaste for the poor to deeply personal father-son issues, in the process.