Hwayi is a boy living in a farm village, who was raised by 5 fathers. His fathers are known criminals and the police nicknamed them as "Daytime Monsters". One day, the group is commissioned to kill a man named Lim and his wife. Apart from the leader Suk-tae, rest of the group feel something odd about this particular contract, but Suk-tae is adamant to carry out this job with Hwayi in tow. This is the first time Hwayi has ever tagged along for a job and discovers a photograph of a child in Lim's house. Suk-tae hands his gun to Hwayi and orders the boy to kill Lim. Despite his plea, Hwayi is forced to pull the trigger. He becomes ill after committing his first kill, and realizes that the boy in the photograph looks uncannily familiar.