Hyun-soo, who suffered from school violence during his school days, imagined taking revenge on the perpetrators through a webtoon. After becoming an adult, he serialized the webtoon titled Hemoglobin's Poem. However, a series of murders began to occur, mirroring the events in the webtoon. Hyun-soo, disturbed by the connection, stopped the serialization to prevent further incidents.
Despite this, the murders continued. Among the characters in the webtoon was Sung-cheol, Hyun-soo's friend from high school, who now becomes a potential suspect or target. To uncover the truth and stop the tragedy, Hyun-soo revisits his past memories and tries to solve the mystery.
Ultimately, Hyun-soo is the only one who can bring an end to the chain of events.