Under The Skin

Seven years ago at North River Yacht Club, artist Shen Yi was painting on the building wall when a mysterious woman asked him to draw how a child in a photo would look as an adult. Seven years later, while teaching at a university, Shen Yi receives a call from Chief Zhang of North River Police, helping them catch a criminal by creating a sketch over the phone.

He Rongyue confirms Liang Yi died of cyanide poisoning. Du Cheng briefs Chief Zhang, who orders them to find the five missing plastic surgery patients. Du Cheng asks secretary Liu Yun to match faces before and after surgery with medical records, but she can only identify some. Shen Yi volunteers and works continuously to restore all faces in the videos to their pre-surgery appearance.

Chief Zhang is pleased with the quick case resolution. Du Cheng unexpectedly accepts Shen Yi's addition to the team and offers to personally help him learn the job at crime scenes. At the police station, three witness artists recognize Shen Yi's distinctive style. Du Cheng discovers Shen Yi disappeared from the art world years ago.

Investigators prioritize determining when the skull was replaced and interviewing Ren Xiaoxuan's classmates. Ren's mother provides her daughter's diary, revealing bullying incidents and a close male relationship from high school.

Shen Yi and Du Cheng discover multiple banyan tree paintings by Ren Xiaoxuan. One painting bears her red lip print overlapping with another-likely belonging to the mysterious boy. After the case, Du Cheng visits Lei Yifei's portrait to honor his mentor and meets Lin Min, Shen Yi's senior colleague. Lin Min reveals Shen Yi's reaction to events seven years ago.

Chief Zhang briefs them on Chu Yingzi's case-a death row inmate who claims an uncaptured accomplice coerced her into murder through marriage fraud. Victims' families protest regularly. Multiple sketch artists produce different images based on Chu's descriptions, indicating deliberate delay tactics.

Hua Muyao is imprisoned by her boyfriend Wen Jing during a date, who demands ransom from her father. She escapes and reports to the police, but Wen Jing's identity cannot be found. Detective Shen Yi sketches his appearance based on her description.

Du Cheng notices Shen Yi acting strangely while working on a child trafficking case. Following him, he discovers Shen Yi is in therapy to recover lost memories from a near-drowning. At the seaside, Shen Yi reveals he's trying to recall a woman from seven years ago.

Shen Yi asks Du Cheng to help him recreate the state of near-drowning to recall the mysterious woman's face. In a life-threatening moment, Shen Yi finally remembers her appearance. Meanwhile, Du Cheng rushes to a jewelry store robbery, while Shen Yi completes the sketch of the woman who has haunted him for seven years.

Shen Yi sketches Xiao An's biological father, but He Hong denies knowing him. Shen Yi recalls seeing the man before, leading to his capture. Meanwhile, He Rongyue discovers He Hong isn't Xiao An's real mother. A 20-year-old photo of He Hong reveals she looks identical to her current self.

Du Cheng and his team find the murdered Xiao Li near He Hong's home. He Rongyue confirms the method matches that of Lei Yifei's killer. He Hong is missing. Meanwhile, in a separate case, a frail and scarred woman, Chen Qiuwen, confesses to killing her husband, Zhao Mingzhe, in a single-apartment homicide.

Du Cheng questions Chen Qiuwen and finds a stun gun near the scene with her fingerprints and Zhao Mingzhe's DNA. Chen admits to killing Zhao after stunning him, claiming it was out of fear he'd retaliate upon waking. Shen Yi suspects she may still be lying.

Shen Yi meets Liu Xiaoye at the hospital and confirms her perception is intact. After Officer Xiao Liu recounts Liu Xiaoye's description of the suspect, Shen Yi sketches the suspect's face. Meanwhile, Shen Yi's mentor, Professor Xu Yiduo, visits the Beijiang Police Station and, after seeing Shen Yi's sketch, pleads with Du Cheng to have Shen Yi resign.

Lin Min asks Shen Yi to organize a gallery for Professor Xu, but he refuses. Du Cheng discovers Xu selling replicas of Shen Yi's paintings. Li Han finds a video of Xu's son demanding money, revealing Xu copied Shen Yi's work to help his son abroad.

Officer Fei arranges a blind date for Du Cheng, where he meets model Xiao Shan. Meanwhile, Shen Yi encounters Du Cheng's sister, Du Qing, during an art lecture. Du Qing asks Shen Yi to persuade Du Cheng to quit being a detective, but Shen Yi believes she doesn't truly understand her brother.

A factory explosion injures Wang Xingjun after opening a detonating package. Shen Yi and Du Cheng find similar cases involving robot toy parts. With no leads, they focus on uncovering links between the victims under a deadline from Director Zhang.

In the early hours, M's body is found in the lobby of the Huige Hotel construction site, while Du Cheng cleans up traces at the scene and takes a watch before leaving. Shortly after, He Rongyue, Shen Yi, and others arrive following a report. Shen Yi confirms the deceased is M, whom he had been searching for, leaving him devastated.

On the way to a dinner arranged by Du Qing, Shen Yi secretly collects some cleaning fluid from Du Cheng's car during a parking stop. At dinner, Shen Yi persistently asks about Du Cheng's watch, and Du Qing eventually presents it-revealing its dial has been replaced with a new one.

Lu Haizhou presents evidence to Director Zhang, who orders Du Cheng to be suspended for investigation. Lu Haizhou reveals to Shen Yi that he came to Beijiang Police Station due to a city bureau report containing M and Du Cheng's call recordings. Shen Yi suspects hidden motives and believes someone may be framing Du Cheng.

Lu Haizhou announces the end of the investigation, and Du Cheng is reinstated. Li Han and the cybersecurity team discover a key server in Chen Zhou's office likely hiding core secrets but requiring the correct password to access. Shen Yi and the team study Chen Zhou's background and devise a plan targeting the secret server.