Ha Jin Gam and Ha Rin Gam, 17 year old twins who are physics genius are just normal students who go to ‘Prime high school’ , a school for gifted students. One day, So Min, a girl who Ha Jin had a crush on killed herself, and people who are related to the case die one by one. The police investigation gets on the way, but it leads to no where because there’s no physical evidence, only suspicion that it might be a murder case. Ha Jin , troubled by So Min’s death, becomes suspicious of a series of murders following her death. And he got attacked by the unknown being. He was saved by his twin Ha Rin, who told him about guardian angels. Ha Rin is one of 1001 good people chosen by guardian angels and Ha Jin is her guardian angel. Ha Jin, who at first didn’t believe the story finds out a series of killings are committed by “somebody” and “guardian angel”. Now Ha Jin believes in guardian angels and the killings are related to each other and the twins are in the center of the whole thing. The beginning of the whole thing was depravity of humans, which has been continuing for a long time and finally turned guardian angels against humans. Ha Jin and Ha Rin find out that after experiencing the events that involve people and their guardian angels around them a bigger plan was in the works and that their school was in the center of the whole scheme. Humans and their guardian angels who want to protect the mankind, And humans and their guardian angels who want to destroy the mankind! In the middle of this war in which every body strives to get an answer to the fundamental question of “good and evil”, Ha Jin thinks seriously of the choice he eventually has to make.