After his promotion to inspector, Jang Jae Gyeong is abducted for three days. Just moments before, he received an SOS text message from a former friend referencing the name "Doctor". The new and potent "Lemon Mulberry" drug is injected into his system and one pill is left in his coat. Suffering withdrawal symptoms and only flashes of what happened to him, he needs to find out the connection between him and this mysterious "Doctor".