The play begins with the back end of the judge's summing-up of the trial, just before he sends out the twelve men of the jury to make their deliberations.
He starts by reminding the jurors that murder in the first degree, premeditated homicide—the crime for which the defendant has been charged—is the most serious charge tried in our criminal courts. Straight away, we're left in no doubt as to the seriousness of what's at stake. The twelve members of the jury have been given an onerous task. They must decide whether the young man before them is a murderer. This task is made all the more weighty because of the fact that the young man will be executed if they, the jury, finds him guilty. As the judge makes clear, one man is dead and the life of another is at stake.
Given the seriousness of the charge, and the seriousness of the consequences that will follow if the defendant is convicted, the judge reminds the members of the jury that they must arrive at an unanimous decision. As subsequent events will show, however, this is easier said than done. It will take significant persuasion by Juror No. 8 to get all men to agree that the defendant is, in fact, innocent.