After an enexpected death, Chan Yoon Hyun loses her bestfriend/childhoodfriend, Kan Eun Sae, in an unsolved mystery. After the funeral, Eun Sae's parents give Yoon Hyun a poster of Eun Sae favorite boy band, B2ST. Little does Yoon Hyun know that it will lead to both the reason of Eun Sae's death and Yoon yun's love life...