The long-standing peace of a conservative small town is shattered by the appearance of an online novel "Abyss." Many plot points bear a striking resemblance to a cold case from years ago that has never been made public. Li Cheng, a passionate and righteous rookie police officer, engages in a series of high-stakes battles of wits with various suspects. He unravels the mystery, revealing the truth buried beneath heartbreaking kinships and friendships.