As the murders continue without a clue as to the killer’s identity, Frank slowly but surely feels his own dark side emerging again, and will do almost anything to find and kill the man responsible, because he thinks it will help him redeem himself for not catching his own daughter’s killer. Meanwhile, Katherine struggles with her own inner demons too, and it almost ends their relationship. Soon, though, as the end of the film draws near, we find out who the killer is in a twist ending you won’t see coming, and Frank and Katherine don’t find satisfaction or redemption, but instead see just how dark all of us can be if provoked too far.