Beneath the Truth:

Cai Jiji, who has dissociative identity disorder, struggles to fall asleep every night. Her second personality, Caixl, kills indiscriminately at midnight. She is tormented by it, but has no choice but to endure. This time, however, she is a detective assigned to investigate a case committed by “herself.” To preserve her own identity, Cai Jiji unknowingly follows Caixl down the path of crime...

Meanwhile, Cai Jiji’s childhood friend, Wang Ba’e, investigates the case alongside her. Only after Cai Jiji traumatizes her two partners, Li Jiji and Zhang Jiji, does she finally understand:

She is my closest friend, my fellow detective, and a wanted serial killer who has taken countless lives.

Who am I, really? Am I Cai Jiji, or Caixl...?