What was the trial about? What was the intial reaction of jurors when they went into the jury room?

Twelve Angry Men is a drama about twelve jurors who have to bring a verdict in a murder trial. A young man, a teenager, is accused of stabbing his father to death with a knife. The judge has instructed the jurors that they must be unanimous in their verdict, explaining that the death penalty is mandatory if they bring a verdict of guilty. When the jurors enter the jury room, it is very hot, and the jurors seem irritable, although some seem thoughtful. A few complain about the trial. After some brief conversation, the leader of the jury calls for a vote. At this initial vote, eleven men vote "guilty," and only one, Juror 8, votes "not guilty." There is some surprise and muttering toward him for being the only one who votes differently, and some jurors demand that he explain himself and even seem to ridicule or taunt him for his "wrong" opinion. Juror 8 explains that he doesn't know if the boy is guilty or not, but that he can't bring himself to be the final vote that will put the boy in the electric chair. He maintains that they should at least discuss the case before they sentence him to death.