This was genuinely a tough watch because the subject matter revolves around school bullying and assault. There is also a lot of gore and violence depicted so it might be hard to watch the first 4 episodes of the series. It gets better after that as the bulk of the worst forms of violence is over.

This is a revenge drama that follows a series of murders committed by a victim of school bullying, Hwang Kyung Min, as an adult shortly after he was suspected of killing his wife. Kyung Min, leaves messages for his school friend, now a police officer, Jung Jong Suk at his crime scenes inviting him to join him. Thus the detective becomes part of the investigation and provides insight into who the potential victims can be. With every episode we are taken to flash backs to experience the intense violence and humiliation that was faced by Hwang Kyung Min for being of lower social status than the rest of the class. At the time, he was befriended by Jung Jong Suk who eventually started to stand up to his friend's bullies and faced their wrath.

The story is intense and gripping. As a viewer, you will find yourself rooting for the main lead as he seeks his revenge. There is another mysterious character introduced and with each episode you understand their relevance to the story. The ending was incredible and unexpected! I hope people are not put off with the gore and make it through to the end. It'll be worth it.