[Contains sensitive themes] Dillon Cossey felt isolated and alone… until he turned to the internet to connect with other victims of bullying which led to him poring over sites about school shootings. Not long after, he was arrested. In this episode, we see how chronic bullying can change the adolescent brain and, along with other significant factors, can lead to violence. Also, we hear from Sue Klebold, mother of one of the Columbine High School shooters.