Adapted from Reginald Rose's television play, this film marked the directing debut of Sidney Lumet. At the end of a murder trial in New York City, the twelve jurors retire to consider the verdict. The man in the dock is a young Puerto Rican accused of killing his father, and eleven of the twelve jurors do not hesitate in finding him guilty.
However, one of the jurors (Henry Fonda), reluctant to send the youngster to his death without any debate, returns a vote of not guilty. From this single event, the jurors begin to re-evaluate the case, as they look at the murder - and themselves - in a fresh light.