Three bizarre murders occur in quick succession in Shuitian Town, and every victim has drowned. Lao Mao, the police officer in charge of the case, discovers that all three deaths were homicides connected to a “ferry sinking” ten years earlier. The victims had all survived aboard the ferry that was traveling from Shuitian Town to the city. Three people drowned in that incident: Lao Mao’s wife, a middle-aged man, and the man’s five-year-old child. Lao Mao deduces that the killer behind the three murders is most likely Ye Qian, the middle-aged man’s wife, who is seeking revenge for her husband and son.
When Lao Mao investigates Ye Qian, he discovers that after the “ferry sinking,” she attempted suicide several times, suffered a mental breakdown, spent five years in a psychiatric hospital, and then mysteriously disappeared.
As he continues investigating, Lao Mao realizes that a woman in town named Song Xianzhen may well be Ye Qian. He launches a full investigation, and after many twists and turns, finally exposes Song Xianzhen’s false identity and proves that she is Ye Qian. Even so, he still cannot arrest her: there is no evidence linking Song Xianzhen, or Ye Qian, to the three murders in town.
Unable to bear watching the killer go free, Lao Mao continues to rack his brains and fight against Ye Qian, determined to bring her to justice.
Besides carefully outmaneuvering the police to protect herself, Ye Qian is planning the final step of her revenge: killing Lao Mao. He was present at the “ferry sinking,” and Ye Qian believes he bears undeniable responsibility for her husband and son’s deaths.
The heavens may have a vast net, but nothing escapes it. After a thrilling battle of wits and a desperate struggle against Ye Qian, Lao Mao finally finds the evidence he needs, arrests her, and solves the case.