6 decades books

A group of 30 teens find themselves locked away in an unknown place, known by the wardens as Judgement. The 30 teens will live in a place where no wind or light of the outside world would reach. The only way out? To commit a perfect murder. If found guilty, the murderer will suffer an execution, if the guilty party is wronged, everyone else besides the murderer faces execution. The survivors will be allowed free once the numbers reaches a bare minimum. Can they keep their calm and survive? Or will they fall into despair?