After wandering around fruitlessly, Yang Guangyao goes to the hospital to visit his daughter, but the doctor can’t find any record of her. He becomes bewildered and rushes to the street, borrowing a coin to make a call, but to no avail. He even returns to his home, but finds no trace of his family.
Next, Yang Guangyao runs to the stairs where he chased the man in black, desperately trying to retrace his steps by taking the elevator. However, he finds himself back where he started, with the same security guard still at the entrance.
Lost and disoriented, he wanders the streets and enters a bar. He notices a police operation taking place inside. An undercover officer demands everyone show their ID. Yang Guangyao instinctively reaches for his, but realizes he doesn’t have it. He turns to leave, but the female officer chases and apprehends him after a brief struggle.
Dejected, Yang Guangyao is taken to the police station. A middle-aged man enters the interrogation room. He is stunned to recognize the man as Yang Yaoguang, who disappeared 20 years ago. Yang Yaoguang also recognizes the man as Liu Weitao, his former trainee, and instinctively grabs his arm, demonstrating a familiar hold. This triggers a flashback in Liu Weitao’s mind, reminding him of his training days. He is shocked and recounts the events of the past 20 years, including how Yang’s wife searched for him all over Hong Kong. Yang Guangyao is reunited with his former colleagues, who are astonished by his unchanged appearance.
Yang Guangyao explains his situation and his desire to find his family and solve the cases before returning to his own time. His former superior, unable to refuse, agrees to let him work undercover as a police officer. He returns to the force under the alias Lu Jiajie. Liu Weitao reminds him to be discreet and adapt to the changes in the police force. They take him to his new apartment and introduce him to a modern cell phone.
Soon, the police station receives a new case. Yang Guangyao arrives at the scene to find the victim drowned in a bathtub, with their phone plugged in and charging. After the initial investigation, Yang Guangyao, resuming his role as a police officer, starts working on the case. He and his partner discover it’s not a simple accident, but a murder.
Meanwhile, Mai Zhihong, still at large after 20 years, continues to commit crimes. He enjoys playing games with the police. Back at the police station, Yang Guangyao discusses the new murder case with his colleagues. Based on the autopsy report, he realizes this case is identical to the serial killings from 25 years ago. They remember the prime suspect from back then, Mai Zhihong, and decide to find him. However, they learn from the mental hospital that he has escaped. Yang Guangyao, furious, blames Liu Weitao for losing track of the suspect. The police are helpless against Mai Zhihong. They examine the murder weapon, a dagger, hoping to find clues.
