Adapted from the "Blue Whale Game" that was circulated on Russian social networks in 2013. The film describes Sungmin and Junhyuk, who live together in the examination hall, and one day they learn that the sister of the examination hall who they have a good relationship with has committed suicide. That night, Sungmin receives a message from the girl's SNS. The two begin to question whether there is a conspiracy behind the suicide. They approach hacker Nuri to find clues from the girl's SNS. The topic that the film wants to convey is: What is SNS to us? When did the SNS that transmits messages in daily life become a channel for crime?