Hu Xiaoman of the CID uncovers a sex trafficking ring while looking for a missing heiress. During her investigation she encounters Da Bao, low level criminal and member of the trafficking ring. While trying to track Bao down, Hu discovers that there is a mole on her team.
While Hu tries to track down the members of the trafficking ring, she and her team walk into a trap. Bao is forced to do something horrible in order to keep her secret safe.
As Detective Hu works a kidnapping, Detective Zheng deals with his demons from his past. A message from Bao sends the CID racing to stop the gang of human traffickers. But things don't go as planned, putting Bao's life in danger.
Detective Zhang is missing after the raid against the human trafficking ring. Bao must trust Detective Hu with her secret that she is a police informant. Can these two women on opposite sides of the law find Zhang before it's too late?
Having been warned by Major Crimes to not get involved In the search for Detective Zhang, Hu tries to solve her two kidnapping cases. When Bao's friend is captured by Savage, leader of the trafficking syndicate, she and Hu race to his rescue.
Major crimes takes over the hunt for Savage, leaving Hu out in the cold. Focusing on the kidnap case, Hu makes a starting discovery. Meanwhile Bao deals with the fallout of Savage's attack on her friends.
The child kidnapping case takes a deadly turn. An abundance of suspects makes it difficult for Hu to find the culprit. Bao comes up with her own theory and decides to test it.
The kidnapper has been found and has confessed to murder, but something about the case bothers Detective Hu. She and Bao try to solve what really happened.
The suicide of a young woman raises questions about several other cases of a similar nature. Hu believes they may be on the trail of a serial killer. Bao tries to help her extended family through some tough times.
A wrinkle in the serial suicide case reveals a new connection to the missing Zhang, raising suspicions of corruption. Bao deals with a death in her extended family while helping Hu with the suicide case.
Office politics and a high level cover up threaten to derail not only Hu's search for Zhang, but her career. The Suicide Killer continues to stay one step ahead of the police and has already found his next victim.
Hu asks Bao's friend Ani to help stop the Suicide Killer before he kills his next victim. Zhang is accused of another murder, forcing Hu to make a difficult decision.
Hot on the trail of the suicide killer, Hu suffers a setback when Ani goes missing. Bao and Hu come up with a dangerous plan to get the killer to reveal himself.
The investigation into Detective Zhang's disappearance comes to a head when Hu is suspended for refusing to drop the case. Determined to learn the truth, she investigates on her own. Meanwhile Bao starts a missing persons charity and gets a client her first day.
Hu juggles the investigation into Zhang's disappearance, her mothers refusal to discuss her relationship with a male prostitute, and Bao's missing persons case. Meanwhile, Bao deals with the fallout of Shi-San's betrayal by his father.
Bao's missing persons case becomes complicated when it appears that identity theft is involved. Hu's investigation into Zhang's disappearance results in one officer dead, the other injured, and no closer to the truth.
The final pieces of the investigation into Officer Zhang's disappearance fall into place. Bao and Hu race to rescue Zhang before his abductor finishes him off.
Zhang has been rescued, and his abductor has been revealed as Dai Wei, Hu's partner. Now she must get a confession while dealing with a horrible betrayal.
